BANSALCLASSES CHEMISTRY TARGET IITJEE2007 XI (P, Q, R, S) 1l l i fW&M::! ' : .'; ;. ; : : ;;;; ATOMICSTRUCTURE CONTENTS rt:coctt:s t+s:co tttttsu:ott coctt: :otcuto+t t:o: +srttrt: PhysicalConstants" Constant and Symbolb Speed of light in vaccumc Proton & electron chargee Permittivity of vaccumo Avogadro constant Na Electron rest massme (0.000548 amu) Proton rest massmp (1.00757 amu) Neutron rest mass (1.00893 amu) Planck constanth Permeability of vaccums Bohr radius ao Bohr's velocity Bohr's energy (-13.6 eV/atom) Bohr magneton (BM) Pe Gas constantR Boltzmann constantk Gravitional constantG EnergyConversionFactors3 SI Value 2.99xl08m/s 1.60x10~19C 8.85x10"12 C2/N-m2 6.02 x 1023 mol"1 9.10x10~31 kg 1.67x 10~27 kg 1.67x 10"27 kg 6.62x10-34 J s 471 x10"7 NC"2s2 5.29x lO^11 m ,Z 2.188 xlO6 x m/sec. n Z2 -21.8xlO"19^2"J/atom 9.27 x10"24 J/T 8.3145 J/mol-K 1.38 x10"23 J/K 6.67 x10"11 m3/kg-s2 1 erg = 10"7 J 1 cal = 4.184 J 1 eV=1.602177 x 10~19 J = 1.602177x 10" 12 erg = 23.0605 kcal/mol GreekAlphabet Gaussian Value 2.99 x 1010 cm/s 4.8x10~10 statC 6.02 x 1023 mol"1 9.10x10-28g 1.67x10~24 g 1.67x10~24g 6.62x10"27 erg s 0.529x10-8cm 2 2.188 xlO8 x cm/sec. n -21.8xi0~12erg/atom 8.3145 x 107erg/mol-K 1.30 x10"16 erg/K 6.67x10~8cm3/g-s2 AlphaAaBetaB P Gmnmar Y DeltaA5 EpsilonE8ZetaZ c EtaHr| Theta0 IotaIiKappaKK LambdaAXMuM NuNvXi H~< Omicron0oPin RhoP P Sigma2a TauTXUpsilonYu Phi ChiX X Psi OmegaQCO (!BansalClasses AtomicStructure[16] KEYCONCEPT STRUCTURE OF ATOM Rutherford's Model Bohr's Model Wave mechanical model EXTRANUCLEARPART(e~) Electrons,protons & neutrons are the most important fundamental particles of atoms of all elements (Except hydrogen) Some uncommon Fundamental particles: 1.zX\ A= Z + n2.m = m0/[l-(v/c)2], / 2 1 11mM 3.Reducedmass-"77 +=m = mass of e~;M = Mass of nucleus HMmm+M h 4.Photon is considered massless bundle of energy. But to find its mass use m =^ 5.E= mc2,E = hv =he/ X = hev no. ofmoleculesreacting 6.Quantum efficiency orQuantum Yield=7I77, ^yno. ofquantaabsorbed 7.Rn = R,(A)1/3,R, =1.33xl0",3cmA = massnumber A11,Z2et6K.zeZe i.Tan =f 8.d.=Noma vf, = K^;Ldn~Z~2k n e u c l e u sN4j3^ J^aa^'2m V. b IT1 number of a particles at 6 =^TT7T; b = impact parameter sin0/ 2 1-9.Rydberg's Equation~~ =v =rH x ,n1n2 xZ2 10.Limiting spectral line (series limit) means n,= oo 11.Ha line means we know nt,n, (longestX, shortest v , least E) [ Ha,Hp , H^, Hg ] n( n- l ) 12.No. of wavelengths observed in the spectrum = whendeexcites to ground state, n = no. of higher orbit 13.1 /2 mv2 =hv -hv(w) (work function or B. E.) he v= Threshhold frequencyW = hv0 =^ 14.Accelerating potential = eV = KE = mv2 15.X=hc/E =1240 ev. nm 2KE 16.v = / K q-,q2K = 'Kq, q2 17.F =2;4tis'=D = dielectric constant, centrifugal force =mr / r Dro'r h 18.mvr = n-=n .h : (!BansalClassesAtomicStructure[16] 19. 20. 22. 24. 25. 26. 28. 30. 34. 36. 38. 40. 42. 44. 45. 46. F=^z227t2me42 n2n VZ n2h2 r=x E, = _ 24 -271me z2ne 21.v =-x nh 23.Time for one revolution = :. "7>.22 Z47tem revolutions per sec = v/27tr Separation energy =-En glven=23A No. of waves = n = no. of shells I.E. = E-E, , f.(K, L, M, N)27.n = n+ nA(Sommerfeld model) n = c og r o u n ds t a t eo r e -v'''Jr/ A 32.v1/2 = a(z-b)b = screening constant33.Radius of.2.8 x10~!3 cm mc' Nucleons Isoelectronic Isodiaphers(A-2Z) Diamagnetic h L=V'C + 1) 2rc 35.Isotopes, Isobars, Isotones (A -Z) 37.Isosters 39.paramagnetic 41.Core, Kernel, core charge, optical e~ [Valence shell, outermost shell, pentultimate shell] h 43.S=VS(S + 1); S=S :2 7i (i=^'n(n + 2)B.M.n = number of unpaired; Radial Nodes (n -/ -1) Angular nodes ; t Total nodes (n-1) Total no. of e" in an energy level= 2n2 Total no. of e- in a sublevel= 2(21+1) Maximum no. of e- in an orbital= 2 Total no. of orbitals in a sublevel= (21+1) No. of subshells in main energyshell= n No. of orbitals in a main energy shell= n2 t0 s 1 P 2 d 3 f (!BansalClassesAtomicStructure[16] 47.ELEECTROMEGNETI CSPECTRUM :> X increases Cosmic Rays y- rays X - Rays Vaccum UV UVVisible Nrar IR Far IR Micro Waves Radio Waves =lO"1410"13 1C meters. lO"11 rI' 10"9 i 10"710"61 0"8 O"5 1 10"3 O"41( 1 r2 0"'10 Distinction between the wave atomic particle. PHOTON 1.Energy = hv c 2.Wavelength = v Note: We should never interchange any of the above and to write electronic conf. of Cation first write for neutral atom & then remove e~ from outermost shell. (!BansalClassesAtomicStructure[16] -particle nature of a photon and the particle-wave nature of sub-SUBATOMI CPARTI CLE Energy = mv2 h Wavelength = mv su+ttsot + :otcott::+ /V The spherical Polar CoordinatesS 22 x - y xy (!BansalClasses AtomicStructure[ 16] .z y ( z2- x2)x3_y3Angular part of the wave function: The figures show shapes of atomic orbitals as polar plots. The direction in which the angular part is positive (negative) is indicated in blue (red). A surface on which the angular part of the wave function vanishes is called an angular node. It may be a plane or the surface of the conc. The s, p, d and f orbitals have 0,1,2, and 3 angular nodes respectively. (!BansalClassesAtomicStructure[16] EASYGO Q. 1Atoms consists of protons, neutrons and electrons. If the mass of neutrons and electrons were made half and two times respectively to their actual masses, then the atomic mass of 6C12. (A) Will remain approximately the same(B) Will become approximately two times (C) Will remain approximately half(D) Will be reduced by 25% Q.2Which of the following is not true in Rutherford's nuclear model of atom (A) Protons and neutrons are present inside nucleus (B) Volume of nucleus is very small as compared to volume of atom (C) The number of protons and neutrons are always equal (D) The number of electrons and protons are always equal Q. 3When a -particles are sent thought a thin metal foil, most of them go straight through the foil because (one or more are correct) (A) Alpha particles are much heavier than electrons (B) Alpha particles are positively charged (C) Most part of the atom is empty space (D) Alpha particles move with high velocity' Q.4Bohr's model can explain (A) The spectrum of hydrogen atom only (B) Spectrum of atom of iron containing one electron only (C) The spectrum of hydrogen molecule (D) The solar spectrum Q. 5The ratio of the energy of a photon of2000 A wavelength radiation to that of4000 A radiation is (A) 1/ 4(B)4(C) 1/ 2(D) 2 Q. 6Bohr model of an atom could not account for (A) Emission spectrum(B) Absorption spectrum (C) Line spectrum of hydrogen(D) Fine spectrum Q. 7The maximum energy is present in any electron at (A) Nucleus(B) Ground state (C) First excited state(D) Infinite distance from the nucleus Q. 8Which electronic level would allow the hydrogen atom to absorb a photon but not to emit a photon (A) 3s(B)2p(C)2s(D) Is Q.9The third line in Balmer series corresponds to an electronic transition between which Bohr's orbits in hydrogen (A) 53(B) 5 - 2(C) 4 3(D) 4 - 2 Q. 10Correct set of four quantum numbers for valence electron of rubidium( Z -37) is (A) 5, 0,0, +^( B) 5 , l , 0 , +|( C) 5 , l , l , + |(D) 6, 0, 0, +\ Q. 11The correct set of quantum numbers for the unpaired electron of chlorine atom is n/mnIm (A)210(B)211 (C)311(D)300 (!BansalClassesAtomicStructure[16] Q.12The orbital diagram in which the Aufbau's principle is violated is 2s2px2p2pz2s2px2p2pz (A)t lt lt(B)fUtt (C)Uttt(D)Ut lUt Q. 13The total number of neutrons in dipositive zinc ions with mass number 70 is (A) 34(B) 40(C) 36(D)38 Q. 14Principal quantum number of an atom represents (A) Size of the orbital(B) Spin angular momentum (C) Orbital angular momentum(D) Space orientation of the orbital Q. 15Which of the following sets of quantum numbers represent an impossible arrangement n / m i r i j .n / r n n ^ (A)32 - 2 ^'(B)400| (C)32-3|(D)530| Q. 16CO has same electrons as or the ion that is isoelectronic with CO is (A)N+(B)CN-(C)O;(D)02 Q. 17The explanation for the presence of three unpaired electrons in the nitrogen atom can be given by (A) Pauli's exclusion principle(B) Hund's rule (C) Aufbau's principle(D) Uncertainty principle Q. 18The maximum number of electrons that can be accommodated in the Mth shell is (A) 2(B) 8(C) 18(D) 32 Q. 19Elements upto atomic number 103 have been synthesized and studied. If a newly discovered element is found to have an atomic number 106, its electronic configuration will be (A) [Rn]5f14,6d4, 7s2'(B) [Rn]5f14, 6d\7s2 7p3 (C) [Rn]5f14,6d6,7s(D) [Rn]5f14,6d5,7s1 Q. 2 0Which quantum number will determine the shape of the subshell (A) Principal quantum number(B) Azimuthal quantum number (C) Magnetic quantum number(D) Spin quantum number Q.21Anisostereis ) -a n uw j(A)NO;and O,(B)NO;andP034"(C) C02,N20,NOT(D)C/OTand OCN" Q.22The electronic configuration of an element is 1 s2 2s2 2p6 3s2 3p6 3d3 4s1. This represents its (A) Excited state(B) Ground state(C) Cationic form(D) Anionic form Q .23Which of the following has maximum number of unpaired electron (atomic number of Fe 26) (A) Fe(B) Fe (II)(C) Fe (III)(D)Fe (IV) Q. 24Which quantum number is not related with Schrodinger equation (A) Principal(B) Azimuthal(C) Magnetic(D)Spin (!BansalClassesAtomicStructure[16] REFRESHYOURCONCEPTS LIGHT Q. 1H- atom is exposed to electromagnetic radiation of 1028 A and gives out induced radiations. Calculate X of induced radiations. Q. 2The wavelength of a certain line in the Paschen series in 1093.6 nm. What is the value of nhjgh for this line. [Rh = 1.0973xl0+7m-' ] Q. 3A certain dye absorbs 4530 A0 and fluoresces at 5080 A0 these being wavelengths of maximum absorption that under given conditions 47% of the absorbed energy is emitted. Calculate the ratio of the no. of quanta emitted to the number absorbed. Q .4The reaction between H, and Br2 to form HBr in presence of light is initiated by the photo decomposition ofBr into free Br atoms (free radicals) by absorption of light. The bond dissociation energy of Br, is 192 KJ/mole. What is the longest wavelength of the photon that would initiate the reaction. Q.5Wavelength of the BalmerHa line (first line) is 6565 A0. Calculate the wavelength of Hp (second line). Q. 6Calculate the Rydberg constant R if He+ ions are known to have the wavelength difference between the first(of the longest wavelength) lines of Balmer and Lyman series equal to 133.7nm. Q.7The quantum yield for decomposition of HI is 2. In an experiment 0.01 moles of HI are decomposed. Find the number of photons absorbed. Q. 8The light radiations with discrete quantities of energy are called. Q. 9What transition in the hydrogen spectrum would have the same wavelength as the Balmer transition, n=4 to n=2 of He+ spectrum. Q. 10Calculate the energy emitted when electrons of 1.0 g atom of hydrogen undergo transition giving the spectral line of lowest energy in the visible region of its atomic spectrum. PLANK'S QUANTUM THEORY Q. ITCalculate the wavelength of the radiation that would cause photo dissociation of chlorine molecule if the CI- CI bond energy is 243 KJ/mol. Q. 12Suppose 10"17 J of light energy is needed by the interior of the human eye to see an object. Flow mam photons of green light(X= 550 nm) are needed to generate this minimum amount of energy. Q. 13Aphoton having X-854 A0 causes the ionization of a nitrogen atom. Give the I.E. per mole of nitrogen in KJ. Q.14Calculate the threshold frequency ofmetalifthe binding energy is 180.69 KJmor1 of electron. Q.15Calculatethebindingenergypermolewhen thresholdfrequency to the wavelength of240 nm. Q.16A metal was irriadated by light of frequency 3.2 x 10!5 S_1. The photoelectron produced had its KE, 2 times the KE of the photoelectron which was produced when the same metal was irriadated with a light of frequency 2.0x10'5 S~]. What is the ionization Energy of metal. Q. 17U.V. light of wavelength 800 A & 700 A falls on hydrogen atoms in their ground satte & liberates electrons with kinetic energy 1.8 eV and 4 eV respectively. Calculate planck's constant. Q. 18The dissociation energy of H, is 430.53 KJ/mol. If H2 is exposed to radiant energy of wavelength 253.7 nm, what % of radiant energy willbe converted into K.E. Q. 19A potential difference of20 KV is applied across an X-ray tube. Find the minimum wavelength ofX-ray generated. Q.20The K.E. of an electron emitted from tungstan surface is 3.06 eV. What voltage would 1? required to bring the electron to rest. (!BansalClassesAtomicStructure[16] BOHR'SMODEL Q.21Calculate energy of electron which is moving in the orbit that has its rad. sixteen times the rad. of first Bohr orbit. -21.7x10~12 Q.22The electron energy in hydrogen atom is given by En =ergs. Calculate the energy required n to remove an e completely from n = 2 orbit. What is the largest wavelength in cm of light that can be used to cause this transition. Q.23Calculate the wavelength in angstrom of photon that is emitted when an e~ in Bohr orbit n=2 returns to the orbit n=l. The ionization potential of the ground state of hydrogen atom is 2.17x10~n erg/atom. Q.24The radius of the fourth orbit of hydrogen atom is 0.85. nm. Calculate the velocity of electron in this orbit. Q.25The velocity of e~ in a certain Bohr orbit of the hydrogen atom bears the ratio 1:275 to the velocity of light. What is the quantum no. "n" of the orbit and the wave no. of the radiation emitted for the transition from the quatum state (n+1) to the ground state. Q.26Electrons of energy 12.09 eV can excite hydrogen atoms. To which orbit is the electron in the hydrogen atom raised and what are the wavelengths of the radiations emitted as it drops back to the ground state. Q.27A doubly ionised lithium atom is hydrogen like with atomic number z = 3. Find the wavelength of the radiation required to excite the electron in Li2+ from the first to the third Bohr orbit. Q.28Estimate the difference in energy between I and II Bohr Orbit for a hydrogen atom. At what minimum at no.atransitionfromn=2ton=lenergylevelwouldresultintheemissionofX-rayswith X = 3.0 x 10~8m? Which hydrogen like species does this at no correspond to. Q.29Find out the no. of waves made by a Bohr electron in one complete revolution in its 3rd orbit. GENERAL Q.30What is de-Broglie wavelength of a He-atom in a container at room temperature. Q.31Through what potential difference must an electron pass to have a wavelength of500 A. Q.32A proton is accelerated to one- tenth of the velocity oflight. If its velocity can be measured with a precision + 1 %. What must be its uncertainity in position. Q.33To what effective potential a proton beam be subjected to give its protons a wavelength of1 xl0~10m. Q.34Calculate magnitude of angular momentum of an ethat occupies1 s, 2s, 2p, 3d, 3p. Q.35Calculate the number of exchange pairs of electrons present in configuration of Cu according to Aufbau Principle including d and s electrons. Q.36He atom can be excited to Is1 2p' by X= 58.44 nm. If lowest excited state for He lies 4857cm-1 below the above. Calculate the energy for the lower excitation state. Q.37Wave functions of electrons in atoms & molecules are called. Q.38The outermost electronic conf. of Cr is. TOUGHROAD Q. 1X-rays emitted from a copper target and a molybdenum target are found to contain a line of wavelength 22.85 nm attributed to the Ka line of an impurity element. The Ka lines of copper (Z=29) and molybdenum (Z = 42) have wavelength 15.42 nm and 7.12 nm respectively. Using Moseley's law, y1/2 = a (Z -b) calculate the atomic number of the impurity element. Q. 2Calculate the energy emitted when electrons of 1.0 g atom of hydrogen undergo transition giving the spectral lines of lowest energy in the visible region of its atomic spectra. Buns illClassesAtomicStructure[11] Q. 31.8 g hydrogen atoms are excited to radiations. The study of spectra indicates that 27% of the atoms are in 3rd energy level and15% of atoms in 2nd energy level and the rest in ground state. If I.P. of H is 21.7 x 1CT12 erg. Calculate-(i)No. of atoms present in III & II energy level. (ii)Total energy evolved when all the atoms return to ground state. Q. 4One mole He+ ions are excited. Spectral analysis showed existence of 50% ions in 3rd orbit, 25% in 2nd and rest in ground state. Calculate total energy evolved when all the ions return to the ground state. Q. 5The energy of an excited H-atom is -3.4 eV. Calculate angular momentum of e-. Q. 6The vapours of Hg absorb some electrons accelerated by a potential diff. of 4.5 volt as a result of which light is emitted. If the full energy of single incident e~ is supposed to be converted into light emitted by single Hg atom, find the wave no. of the light. Q. 7The hydrogen atom in the ground state is excited by means of monochromatic radiation of wavelength xA. The resultingspectrum consists of15 different lines. Calculate the value of x. Q. 8The eyes of certain member of the reptile family pass a single visual signal to the brain when the visual receptors are struck by photons of wavelength 850 nm. If a total energy of 3.15 x 10 ~14 J is required to trip the signal, what is the minimum number of photons that must strike the receptor. Q. 9If the average life time of an excited state of H atom is of order 10~8 sec, estimate how many orbits an e~ makes when it is in the state n = 2 and before it suffers a transition to n=1 state. Q. 10Calculate the frequency of e~ in the first Bohr orbit in a H-atom. Q. 11What is de Broglie wavelength associated with an e~ accelerated through P.D. = 100 KV. Q. 12A single electron orbits around a stationary nucleus o f charge +Ze where Z is a constant from the nucleus and e is the magnitude of the electric charge. The hydrogen like species required 47.2 eV to excite the electron from the second Bohr orbit to the third Bohr orbit. Find (i)the value of Z and give the hydrogen like species formed. (ii)the kinetic energy and potential energy of the electron in the first Bohr orbit. Q. 13A stationary He+ ion emitted a photon corresponding to a first line of the Lyman series. The photon liberated a photon electron from a stationary H atom in ground state. What is the velocity of photoelectron. Q. 14To what series does the spectral lines of atomic hydrogen belong if its wave number is equal to the difference between the wave numbers of the following two lines of the Balmer series 486.1 and 410.2 nm. What is the wavelength of this. Q. 15A particle of charge equal to that of an electron and mass 208 times the mass of the electron moves in a circular orbit around a nucleus of charge +3e. Assuming that the Bohr model ofthe atom is applicable to this system, (a) derive an expression for the radius of the nth bohr orbit, (b) find the value of n for which the radius of the orbit is approximately the same as that of the first Bohr orbit for th ehydrogen atom, and (c) find the wavelength ofthe radiation emitted when the revolving particle jumps from the third orbit to thefirst. Q. 16A neutrons breaks into a proton and an electron. This decay of neutron is accompanied by release of energy. Assuming that 50% of the energy is produced in the form of electromagentic radiation, what will be thefrequency of radiation produced. Will this photon be sufficient to cause ionization ofAluminium. In case it is able to do so what will be the energy of the electron ejected from the Aliuninium atom. IE, =ofAl=577 KJ/mol Q.17Find the number of photons of radiation of frequency 5 x 1013s_I that must be absorbed in order to melt one gm ice when the latent heat of fusion of ice is 330 J/g. Q. 18A base ball of mass 200 g is moving with velocity 30 x 102 cm/s. If we can locate the base ball with an error equal in magnitude to the A, of the light used (5000 A), how will the uncertainty in momentum be compared with the total momentum of base ball. (!BansalClassesAtomicStructure[16] Q.19 Q.20 Q.21 Q.22 Q.23 Q.24 Q.25 Q.26 The dye aeriflavine, when dissolved in water, has its maximum light absorption at 4530 A and its maximum fluorescence emission at 5080 A. The number of fluorescence quanta is, on the average, 53% of the number of quanta absorbed. Using the wavelengths of maximum absorption and emission, what % of absorbed energy is emitted as fluorescence? An electron has a speed of 40 m/s, accurate up to 99.99%. What is the uncertainity in locating its position. Hydrogen atom in its ground state is excited by means of monochromatic radiation of wavelength 975A. How many different lines are possible in the resulting spectrum? Calculate the longest wavelength amongst them. An alpha particle after passing through a potential difference of 2 x 106 volt falls on a silver foil. The atomic number of silver is 47. Calculate (i) the K.E. of the alpha-particle at the time of falling on the foil, (ii) K.E. of the a - particle at a distance of 5 x 10~14m from the nucleus, (iii) the shortest distance from the nucleus of silver to which the a-particle reaches. Calculate the de-broglie wavelength associated with motion of earth (mass 6 x 1024 Kg) orbiting around the sun at a speed of 3 x 106 m/s. ke2 Use Q.27 (a) (b) Q.28 Q.29 Suppose the potential energy between electron and proton at a distance r is given by3 3r Bohr's theory to obtain energy of such a hypothetical atom. An energy of 68 eV is required to excite a hydrogen like atom from its second Bohr orbit to the third. The nuclear charge is Ze. Find the value of Z, the kinetic energy of the electron in the first Bohr orbit and the wavelength of the radiation required to eject the electrons from the first Bohr orbit to infinity. A proton captures a free electron whose K.E. is zero & forms a hydrogen atom of lowest energy-level (n = 1). If a photon is emitted in this process, what will be the wavelength of radiation? In which region of electromagnetic spectrum, will this radiation fall? (Ionisation potential of hydrogen =13.6 volt, h = 6.6 x 10_34K/s, C = 3.0 x 10s m/s) The ionisation energy of the hydrogen atom is given to be 13.6 eV. A photon falls on a hydrogen atom which is initially in the ground state and excites it to the (n=4)state. show this transition in the energy-level diagram & calculate the wavelength of the photon. Calculate Total spin and the multiplicity for each possible configuration of N-atom. (A) El IE! Km (B)EI M HZH (c)^ [x]to IEI m Find the wavelength of the first line of He+ ion spectral series whose interval between extreme line is -= 2.7451xl04cm-1 Q.30The ionisation energy of a H-like Bohr atom is 4 Rydbergs (i)What is the wavelength of radiation emitted when the e~ jumps from the first excited state to the ground state. (ii)What is the radius of first Bohr orbit for this atom. [ 1 Rydberg = 2.18 x 10"18 J] -6.8 eV(D)+ 6.8 eV 1999 Q. 11The electrons, identified byn & I;(i)n = 4 ,/= 1(ii)n = 4 ,/= 0 (iii)n = 3 ,1=2(iv) n = 3,1 = 1 can be placed in order of increasing energy, from the lowest to highest as : (A)(iv)sp> sp3(D)sp3 >sp>sp2 Q. 57When2s-2s,2p-2pand2p-2sorbitals overlap, the bond strength decreases in the order: (A)p-p>s-s>p-s(B)p-p>p-s>s-s(C)s-s>p-p>p-s(D)s-s> p-s>p-p Q.58The shapes of IFS andIF7are respectively: (A) square pyramidal and pentagonal bipyramidal(B) octahedral and pyramidal (C) trigonal bipyramidal and square antiprismatic(D) distorted square planar and distorted octahedral Q. 59Carbon atoms inC2 (CIV)4are: (A) ^-hybridized(B)sp2 -hybridized (C) sp- andsp2hybridized(D) sp,sp2andsp3 - hybridized Q. 60C02has the same geometry as: (I) HgCl2(II)N02(IE)SnCl4(IV)C,H2 (A) I and III(B) Hand IV(C) I and IV(D) III and IV Q. 61Strongest bond is formed by the head on overlapping of: (A) 2s- and 2p- orbitals(B) 2p- and 2p- orbitals (C) 2s- and 2s- orbitals(D)A11 Q. 62The ratio of aand n bonds in benzene is: (A) 2(B)6(C)4(D)8 - axis(C) z - axis(D) any direction Q. 73Indicate the wrong statement: (A) A sigma bond has no free rotation around its axis (B)p-orbitals always have only sideways overlap (C) s-orbitals never form k - bonds (D) There can be more than one sigma bond between two atoms Q.74sp3hybridisation is in: (A)AIH~(B)CH;(C)C102(D)NH~2 Q.7 5Which of the following pairs is (are) isostructural? (A)SF4 and SiF4(B)SF6 and SiF2'(C)SiF2'and SeF2'(D)XeO*~and TeF2' Q. 76Which of the following has (have) octahedral geometry: 5 -(A)SbCl;(B)SnCl2'(C)XeF6(D) 10, Q.77Shape of NH3is very similar to : (A)SeO2'(B)CH;(C)BHs(D)CH+3 Q. 78Which of the following have same shape asNH2 ? (A)C02(B)SnCl2(C)S02(D) BeCl2 Q.79Which of the following is (are) linear ? (A)/ "(B)i;(C)PbCl2(D) XeF2 Q. 8 0Which of the following species are linear ? (A)ICl2-(B) I3'(C)AT-(D)C102 Cl>Sot>S>Cl (C) S>Clt(D)Cl>St Q. 170If a molecule MX3 has zero dipole moment, the sigma bonding orbitals used by A/(atm. no. < 21) are: (A) pure/?(B) sp hybrid(C) sp2hybrid(D) sp1 hybrid Q. 171How many sigma and pi bonds are present in tetracyanoethylene ? (A) Nine o and nine 7t(B) Five k and nine o(C) Nine aand seven n (D) Eight o and eight iz Q. 172Among the following species, which has the minimum bond length ? (A )B2(B)C2(C)F2(D)02 Q. 173Which has higher bond energy: (A)F2(B )Cl2(C)Br2(D)/2 Q. 174The bond angle intu:is: (A) Much lesser thanu:(B) Equal to that inu:(C) Much greater than inu:(D) Slightly more than inu:Q. 175uoubond angle inouis: (A) 180(B)120(C) 109(D)90 Q.176In the series ethane, ethylene and acetylene, thecubond energy is: (A) The same in all the three compounds(B) Greatest in ethane (C) Greatest in ethylene(D) Greatest in acetylene Q. 177Which one of the following compounds has bond angle as nearly 90 ? (A) u:(B) u:s(C) u:(D)/c Q. 178Of the following species which has the shortest bond length o o

:and oQ. 179Arrange the following species in decreasing order of bond angle. NO+,NO2,NO; Q. 180In the hydrides of group VI elements the central atoms involve sp3hybridisation but the bond angles decrease in the order, u: u2S,u2Si,u2Te. How would you account for this ? P = As = Bi(B)B>P>As>Bi( C) B Br.[ JEE '93] Q.9Diamondis harderthangraphite.[JEE' 93] Q.10Thebasicnatureofhydroxidesofgroup 13 (III B) decreasesprogressivelydownthe group. [JEE' 93] Q.llThetendencyforcatenationismuchhigherforC thanSi.[ JEE'93] Q. 12ThedipolemomentofCH3 FisgreaterthanCH3C1.[ JEE '93] Q.13HBrisstrongeracidthanHIbecauseofH-bonding.[JEE' 97] Q.14Fatomhasless negative EAthan CI atom.[JEE' 97] Q.15LiCl is predominantly a covalent compound.[ JEE '97] Q.16Al(OH)3 is amphoteric in nature.[JEE' 97] Explain the following.[ 11 x 3 = 33] Q. 1Explain the molecule of magnesium chloride is linear whereas that of stannous chloride is angular. [JEE' 87] Q.2Givereasoncarbonoxygenbondlengthsinformicacidare1.23 A0& 1.36Aandboth the carbonoxygenbondsinsodiumformate havethesamevaluei.e.1.27A.[JEE'88] Q.3Givereason that valency of oxygenis generallytwo whereas sulphur shows of2 ,4, & 6. [ JEE '88] Q.4ExplainthefirstI.E.ofcarbonatomisgreaterthanthatof boronatom whereasthe reverseis truefor thesecondI.E.[JEE' 89] Q. 5Explain why the dipolemoment of NH3 is more than that of NF3.[ JEE '95] Q.6TheexperimentallydeterminedN-Fbondlength in NF3isgreaterthan thesumof single bond covalent radiiofN &F . Explain.[ JEE *95] Q.7Explainthedifference inthenatureofbondinginLiF&Lil.[JEE' 96] Q.8Comparequalitativelythe1st&2ndIPofCu&Zn.Explaintheobservation.[JEE' 96] Q.9ExplainPC15isformedbutNC15cannot.[JEE'97] Q.10Give reasons for the following in one or two sentences only.[JEE' 99] (a)BeCl2can be easily hydrolyed(b) Cr03 is an acid anhydride . Q.llExplain why o-hydroxybenzaldehyde is a liquid at room temperature, while p-hydroxybenzaldehyde is a high melting solid.[JEE' 99] Na+ + e~~. ReductionHalfReaction:F2 + 2 e~~> 2F~~ . COMMONOXI DATI ONANDREDUCTI ONPARTS OXIDATIONPARTSREDUCTIONPARTS Fe2+Fe3+ Fe3+ > Fe2+ Zn> Zn2+ x->x2 x2 >X~ S2-^sCr2072 >Cr3+ H2O2 O2NO3- > NO S032->S042- Mn04-~> Mn2+ (neutral med.) C242">C02 Mn04-~> Mn02 (Basic med.) S2O32->s4062-so42->so2 I2-> I03- Mn02 Mn2+ TypesOfRedoxReduction: Intermolecular redox, disproportion, Intra molecular redox. Disproportion: In such reactions the oxidising and reducing agents(atom) are the same. oxidation H2 2+H2 2> 2H, 0+02. reduction To identify whethera reaction is redox or not, find change in oxidation number or loss and gain of electrons. If there is no change in oxidation number, the reaction is not a redox reaction. AutoOxidation:Mn04~ Mn042+ 02. In thisMn inMn04~is reduced. Oxygen in Mn04~~is oxidised. The same sub. Mn04acts as oxidising & reducing agent. This is called auto oxidation. NOTE :To predict the product of reactionremember: (a)Free halogen on reduction gives halide ion(F2 -> F - ) (b)Alkali metals on oxidation give metallic ion with + 1 oxidation state. (c)Cone. HN03on reduction gives N02,while dilute HN03 can give NO, N2, NH4+or other products depending on the nature of reducing agent and on dilution. (d)In acid solution KMn04 is reduced to Mn2+ while in neutral or alkaline, it givesMn02or K2Mn04. (e)H202 on reduction gives water and on oxidation gives oxygen. (f)Dichrornate ion in acid solution is reduced to Cr3"1". Acidic(Mn207) MetathesisReactions: Never redox reactions. In these two compounds react to form two new compounds and no change in oxidation number occur.eg. (i)Pb (N03)2+ K^CrC^ Pb Cr04+2 KN03(ii)HCl + NaOH >NaCl +H20 RulesForAssigningOxidationNumber: (i)Oxidation number of free elements or atoms is zero . (ii)Oxidation number of allotropes is zero . (iii)Oxidation number of atoms in homo-nuclear molecules is zero . (iv)Oxidation number of mono-atomic ions is equal to the algebric charge on them. (v)Oxidation number of F in compounds is - 1. (vi)Oxidation number of H in its compounds is + 1, except in metalhydrides where it is - 1. (vii)Oxidation number of O is - 2 in its compounds, but in F20 it is + 2 and in peroxides it is - 1 and -0.5 in K02. (viii)Oxidation number of alkali metals in their compounds + 1. (ix)Oxidation number of alkaline earth metals in their compounds is + 2 . (x)Oxidation number of an ion is equal to its charge. (xi)Oxidation number of a molecule as a whole is zero . (xii)The sum of oxidation number of all the atoms in a molecule should be zero and in an ion equal to its charge. MOSTCOMMOMOXIDATIONSTATESOFREPRESENTATIVEELEMENTS GroupOuter shell configurationCommon oxid. states except zero infree state IAns1 + 1 IIAns2 + 2 III Ans2np1 + 3,+1 IV Ans2np2 + 4, +3, +2, +1, - 1, - 2, - 3, - 4 VAns2np3 + 5, +3, +1, - 1, - 3 VIAns2np4 +6 , +4 , +2 , - 2 VII Ans2np5 + 7, +5, +3, +1, -1 AverageOxidationNumber:FindOxidationNumber ofFeinFe304. Fe304is FeO.Fe203. O.N.ofFe in FeO is+ 2;O. N.ofFe in Fe203is+ 3 . +2+2x(+3)8 ThereforeaverageO.N.of threeFeatoms =r=+r Product Where 'a' molecules of "analysis", Areacts with t molecules of reagent T. T is called Titrant normally taken in buret in form of solution of known concentration. The solution of titrant is called "standard solution". The addition of titrant is added till the amount ofT, chemically equivalent to that of'A' has been added. It is said equivalent point of titration has been reached. In order to know when to stop addition of titrant, a chemical substance is used called indicator, which respond to appearance of excess of titrant by changing colour precisely at the equivalence point. The point in the titration where the indicator changes colour is termedthe 'end point'. It is possible that end point be as close as possible to the equivalence point. The term titration refer's to process of measuring the volume of titrant required to reach the end point. For many years the term volumetric analysis was used rather than titrimetric analysis. However from a rigoronsstandpointthe termtitrimetricis preferable because volumemeasurementmay notbe confirmed to titration. In certain analysis, for example one might measure the volume of a gas. We can adopt mole method in balanced chemical reactions to relate reactant and products but it is more easier to apply law of equivalents in volumetric calculations because it does not require knowledge of balanced chemical reactions involved in sequence. Law of equivalents refers to that, equivalents of a limiting reactant is equal to equivalent of other reactant reacting in a chemical reaction or equal to equivalents of products formed in reaction. n-factorin non-redoxsystem n factor here we mean a conversion factor by which we divide molar mass of substance to get equivalent mass and it depends on nature of substance which vary from one condition to another condition. We can divide n-factor calculations in two category. (A) when compound is not reacting. (B) when compound is reacting. Acid-Basetitration To find out strength or concentration of unknown acid or base it is titrated against base or acid of known strength. At the equivalence point we can know amount of acid or base used and then with the help of law of equivalents we can find strength of unknown. Meq of acid at equivalence point = Meq of base at equivalence point H,CO,+ NaCl When we use phenophthalein in the above titration it changes its colour at first end point when NaHCO. is formed and with it we can not know second end point. Similarly with methyl orange it changes its colour at second end point only and we can not know first end point. It is because all indicator changes colour on the basis of pH of medium.So in titration of NaHC03, KHCO, against acid phenolphthalein can not be used. So we can write with phenolpthalein, if total meq ofNa2CO. = 1then V2 meq of Na2C03 = meq of HCl with methyl orange, meq of Na2C03= meq of HCl TitrationIndicatorpH Rangen factor Na2C03NPhenolphthalein8.3-101 against acid K2CO3 JMethyl orange3.1-4.42 Note: When we carry out dilution of solution, meq eq, milli mole or mole of substance does not change because they represent amount of substance, however molar concentration may change. Solubilitiesofsomeimportantsalt's: 1.Chloride:AgCl -White ppt. Hg2Cl2- White ppt.All other chlorides are soluble in water. PbCl2-White ppt. CuCl -Insolution ppt. BiOCl-White ppt. SbOCl-White ppt. Hg2OCl2 -White ppt. 2Ag,Se(s) + Ag2Se03 (s) + 6NH4+ The mixture was next treated with excess nitric acid which dissolves the Ag2SeO, butnot the Ag,Se. The Ag+ from the Ag2Se03 and excess AgN03 consumed16.74 mi of 0.0137 NKSCNin a Volhard titration. How many milligrams of Se were contained per millilitre of sample. HAsO, + 3H++3C1~. The amount ofHAsO, was determined by titration with 0.04134 MI2, requiring 23.04 mL to reach ihe equivalence point. The redoxproducts in the titration were H3As04 and I. Find the amount of KMn04 needed to oxidize As in As,03 to its maximum possible oxidation state in acidic medium. Q.17A sample of steel weighing 0.6 gm and containing S as an impurity was burnt in a stream of O,, when S was converted to its oxide SO,. SO, was thenoxidized to S04~~ by using H20, solution containing 30ml of 0.04 M NaOH. 22.48 ml of0.024 M HCl was required to neutralize the base remaining after oxidation. Calculate the % of S in the sample. Q.183.6 g of Mg is burnt in limited supply of oxygen. The residue was treated with 100 mL of H,S04 (3 5% by mass, 1.26 g mL"1 density). When 2.463 L of H2 at 760 mmHg at 27C was evolved". After the reaction, H,S04 was found to have a density of 1,05 g mL"1. Assuming no volumechange in H2S04 solution. Find (i)%by mass of final H,S04 (ii)% by mass of Mg converted to oxide (iii)mass of oxygen used. (Mg = 24, S= 32)Metal reacts with acids to displace H,gas Cu,0+ H20 It is sometimes more convenient to determine the reducing power of a carbohydrate by an indirect method. In this method 43.2 mg of the carbohydrate was oxidized by an excess of K3(Fe(CN)6). The Fe(CN)64" formed in this reaction required 5.29 ml of0.0345 N CefSO^ for reoxidation to Fe(CN)63. Determine the RCu value for the sample. Q.1412.0 g of an impure sample of arsenious oxide (acting as acidic oxide) was dissolved in water containing 7.5g of sodium bicarbonate and resulting solution was diluted to 250 ml. 25 ml of this solution was completely oxidized by 22.4 ml of a solution of iodine. 25ml of this iodine solution reacted with same volume of a solution containing 24.8g of hydrated sodium thiosulphate (Na2S203-5H,0) in one litre. Calculate the percentage of arsenious oxide in the sample. Also reportthe % purity of NaHC03. T2) dQTI~T2I Thermal current -T> dT%h Where thermal resistanceR^ 2.Differential formofOhm'sLaw dQdTdT = KA---~ = temperature gradient dTdxdx KA TT-DT dx IiBansal ClassesCalorimetry& HeatTransfer14] (B)Convection: Heat transfer due to movement of medium particles. (C)Radiation: Every body radiates electromagnetic radiation of all possible wavelength at all temp>0 K. 1.Stefan's Law:Rate of heat emitted by a body at temp T K from per unit area E = oT4 J/sec/m2 dQ Radiation power= P = oAT4 watt If a body is placed in a surrounding of temperature Ts dQ =aA(T4-Ts4) valid only for black body heat from generalbody Emissivity or emmisive powere =b l a c k If temp of body falls by dT in time dt ^= ^(T4 -Ts4)(dT/dt = rate of cooling) dtmS 2.Newton'slaw ofcooling If temp difference of body with surrounding is small i.e. T = Ts soa ( T - T ) dt 3.Average formof Newtonslaw of cooling If a body cools from T, to T2 in time s t T, - T,Kf%+T,^ li12 5tmS T 2s vzy (used generally in objective questions) dTK = (T -T )(for better results use this generally in subjective) dtmS 4.Wein's black bodyradiation At even/ temperature (>0K) a body radiates energy radiations of all wavelengths. According to Wein's displacement law if the wavelength corresponding to maximum energy is then Xm7 = bwhere b = is a constant (Wein's constant) T=temperature of body IiBansalClassesCalorimetry& HeatTransfer14] EXERCISE-III Q. 1An aluminium containerof mass100 gm contains 200 gm of ice at -20C. Heat is added to the system at the rate of 100 cal/s. Find the temperature of the system after 4 minutes (specific heat of ice = 0.5 and L = 80 cal/gm,specific heat of AI = 0.2 cal/gm/C) Q.2A U-tube filled with a liquid of volumetric coefficient of 10"5/C lies in a vertical plane. The height of liquid column in the left vertical limb is 100 cm. The liquid in the left vertical limb is maintained at a temperature = 0C while the liquid in the right limb is maintained at a temperature = 100C. Find the difference in levels in the two limbs. Q.3A thin walled metal tank of surface area 5m2 is filled with water tank and contains an immersion heater dissipating1kW. The tank is covered with 4 cm thick layerof insulation whose thermal conductivity is 0.2 W/m/K. The outer face of the insulation is 25C. Find the temperature of the tank in the steadystate Q.4A glass flask contains some mercury at room temperature. It is found that at different temperatures thevolumeofairinsidetheflask remainsthesame.Ifthevolumeofmercuryinthe flask is 300 cm3, then find volume of the flask (given that coefficient of volume expansion of mercury and coefficient oflinear expansion of glass are 1.8 * 10"1 (C)_1 and 9 x 106 (C)_1 respectively) Q.5A clock pendulum made of invar has a period of 0.5 sec at 20C. If the clock is used in a climate where average temperature is 30C, aporoximately.How much fast orslow will the clock run in iO6sec.(ainvar=lxl0^/C) Q.6A pan filled with hotfood cools from 50.1 C to 49.9C in 5 sec. How long will it take tocool from 40.1 C to 39.9C if room temperature is 30C? Q.7A compositerodmade of three rodsof equal length andcross-sectionas shown in the fig. The thermal conductivities of the materials of the rods are K/2, 5K and K respectively. The end A and end B are atconstant temperatures. All heat entering the face A goes out of the end B there being no loss of heat from the sides of the bar. Find the effective thermal conductivity of the bar K / 25 KK Q.8An iron bar (Young's modulus =1011 N/m2,a=10~6 /C)1m long and10~3 m2 in area is heated from 0C to100C without being allowed to bend or expand. Find the compressive force developed inside the bar. Q.9Asolidcoppercubeandsphere,bothofsamemass&emissivityareheatedtosameinitial temperatureand keptunderidenticalconditions.Whatis theratioof theirinitial rateof fall of temperature? Q.10A cylindrical rod with one end in a stream chamber and other end in ice cause melting of 0.1 gm of ice/sec. If the rod is replaced with another rod of half the length and double the radius of first and thermal conductivity of second rod is1/4 that of first, find the rate of ice melting in gm/sec l|Bansal ClassesCalorimetry& HeatTransfer[12] Q.llThree aluminium rods of equal length form an equilateral triangle ABC. Taking 0 (mid point of rod BC) as the origin. Find the increase in Y-coordinate per unit change in temperature of the centre of mass of the system. Assume the length of the each rod is 2m, and ot^ =4 V3 x 10~6 / C Q.12 Q.13 Q.14 Q.15 Three conducting rods of same material and cross-sectionare shown infigure. Temperatureof ADandC are maintainedat20C,90Cand0C.Findthe ratio of length BD and BC if there is no heat flow in AB 20C 90C 0C If two rods of layer L and 2 L having coefficients of linearexpansion aand 2arespectivelyare connectedso that total length becomes 3 L, determine the average coefficient of linear expansion ofthe composite rod. A volume of 120 ml of drink (half alcohol + half water by mass) originally at a temperature of 25C is cooled by adding 20 gm ice at 0C. If all the ice melts, find the final temper ature of the drink, (density of drink = 0.833 gm/cc,specific heat of alcohol = 0.6 ca!/gm/C) A solid receives heatby radiation over its surface at the rateof 4 kW. The heatconvectiourate from the surface of solid to the surrounding is 5.2 kW, and heat is generatedat a rate of 1.7 kW overthevolumeofthesolid.Therateofchangeoftheaveragetemperatureofthesolidis 0.5Cs"1. Find the heat capacity of the solid. Q.16The figure shows theface andinterface temperatureofacomposite slab containing of four layers of two materials having identical thickness. Under steady state condition, find the value of temperature 0. 20CLQ'CE-5C ~10C 2k2k k =thermalconductivity Q.17 Q.18 Q.19 Two identical calorimeter A and B contain equal quantity of water at 20C. A 5 gm piece of metal X of specific heat0.2 cal g"1(C)_1 is droppedinto A and a5 gm piece of metal Y into B. The equilibrium temperature in A is 22C and in B 23C. The initial temperature of both the metals is 40C. Find the specific heat of metal Y in cal g"1(C0)-1. Two spheres of same radius R have their densities in the ration 8 : 1 and the ratio of their specifr heats are 1 : 4. If by radiation their rates of fall of temperature are same, then find the ratio of their rates of losing heat. In the square frame of side I of metallic rods, the corners A and C are maintainedat Tj and T2 respectively. The rate of heat flow from A to C is co. If A and D are instead maintained T, & T2 respectivley find, find tiie total rate of heatflow. Q.20A hot liquid contained in a container of negligible heat capacity loses temperature at rate 3 K/min, justbefore itbeginstosolidify. Thetemperatureremainsconstantfor30 min.Findtheratioof specific heat capacity of liquid to specific latent heat of fusion is in K_1 (given that rate of losing heat is constant). IiBansal ClassesCalorimetry& HeatTransfer 14] Q. 21A thermostatted chamber at small height h above earth's surface maintained at 30C has a clock fitted in it with anuncompensated pendulum. The clock designer correctly designs it for height h, but for temperature of 20C. If this chamber is taken to earth's surface, the clock init would click correct time. Find the coefficient of linear expansion of material of pendulum, (earth's radius is R) Q.22The coefficient of volumeexpansionof mercury is 20 times the coefficient of linear expansion of glass. Find the volume of mercury that must be poured into a glass vessel of volume V so that the volume above mercury may remain constant at all temperature. Q.23Two 50 gm ice cubes are dropped into 250 gm of water ion a glass. Ifthe water was initially at a temperature of25Candthetemperatureofice-15C.Findthefinaltemperatureofwater, (specific heat of ice = 0.5 cal/gm/C and L = 80 cal/gm) Q. 24Water is heated from 10C to 90C in a residential hot water heater at a rate of 70 litre per minute. Natural gas witha densityof1.2 kg/m3 is usedin the heater,which hasa transfer efficiency of 32%. Find the gas consumption rate in cubic meters per hour, (heat combustion for natural gas is 8400 kcal/kg) Q.25A metal rod A of 25cm lengths expands by 0.050cm. When its temperature is raised from 0C to 100C, Another rod B of a different metal of length 40cm expands by 0.040 cm for the same rise in temperature. A third rod C of 50cm length is made up of pieces of rods A and B placed end to end expands by 0.03 cm on heating from 0C to 50C. Find the lengths of each portion of the composite rod. Q.26 Q.27One end of copper rod of uniform cross-section and of length 1.5 meters is in contact with melting ice and the other end with boiling water. At what point along its length should a temperature of200C be maintained, so that in steady state, the mass of ice melting is equal to that of steam produced in the same interval of time? Assume that the whole system is insulated from the surroundings. Q.28Twosolidsspheresareheatedtothesametemperatureandallowedtocoolunderidentical conditions.Compare:(i) initialratesof fall of temperature,and(ii) initialratesof loss of heat. Assume that all the surfaces have the same emissivity and ratios of their radii of, specific heats and densities are respectively1 : a,1 : p,1 :y. Q.29A vessel containing100 gm water at 0C is suspended in the middle of a room. In15 minutes the temperature of the water rises by 2C. When an equal amount of ice is placed in the vessel, it melts in 10 hours. Calculate the specific heat of fusion of ice. Q.30The maximum in the energy distribution spectrum of the sun is at 4753 A and its temperature is 6050K. What will be the temperature of the star whose energy distribution shows a maximum at 9506 A. A substance is in the solid form at 0C. The amount of heatadded to this substance and its temperature areplottedinthefollowinggraph. Iftherelative specific heatcapacityof thesolidsubstance is 0.5, findfrom the graph the mass of the substance ; the specific latent heat of the melting process, and the specific heat of the substance in the liquidstate. (calories) IiBansal ClassesCalorimetry& HeatTransfer 14] EXERCISE-II Q. 1A coppercalorimeterof mass100 gm contains 200 gm of a mixture of ice and water.Steam at 100C under normal pressure is passed into the calorimeter and the temperature of the mixture is allowed to rise to50C. If the mass of the calorimeter and its contents is now 330 gm, what was the ratio of ice and water in the beginning? Neglect heat losses. Given:Specific heat capacity of copper = 0.42x 103 J kg-'K1, Specific heat capacity of water = 4 ,2 x103 J kg_1K_1, Specific heat of fusion of ice= 3.36x 105 J kg-1 Latent heat of condensation of steam = 22.5x105 Jkg-1 Q.2Anisoscelestriangteis form edwitharodo f length /, and coefficient of linear expansion a,for the base and two thin rods each of length l2 and coefficient of linear expansion a2 for the two pieces, if the distance between the apex and the midpoint of the base remain unchanged as the temperatures lxja^ varied show thatT~2J hVai Q.3A solid substance of mass10 gm at -10C was heated to -2C (still in the solid state). The heat required was 64 calories. Another 880 calories was required to raise the temperature ofthe substance (now in the liquidstate) to1C, while 900calories was requiredtoraise the temperature from -2Cto 3C. Calculate the specific heat capacities of the substances in the solid and liquid state in calories perkilogramper kelvin.Show thatthe latent heatof fusion L is relatedtothe melting point temperature tm by L = 85400 + 200 tm. Q.4A steel drill making180 rpm is used to drill a hole in a block of steel. The mass of the steel block and the drill is180 gm. If the entire mechanical work is used up in producing heat and the rate of raise in temperatureof the block and the drill is 0.5 C/s. Find (a)the rate of working of the drill in watts, and (b)the torque required to drive the drill. Specific heat of steel = 0.1 and J = 4.2 J/cal. Use: P = x co Q.5A brass rod of mass m = 4.25 kg and a cross sectional area 5 cm2 increases its length by 0.3 mm upon heating from 0C. What amount of heat is spent for heating the rod? The coefficient of linear expansicl for brass is 2xl0~5/K, its specific heat is 0.39 kJ/kg.K and the density of brass is 8.5 x 103 kg/m3. Q.6A submarine made of steel weighing109 g has to take108 g of water in order tosubmerge when the temperature of the sea is10C. How much less water it will have to take in when the sea is at 15C? (Coefficient of cubic expansion of sea water = 2 xlO^/X,coefficient of linear expansion of steel =1.2 x10~5/C) Q.7A flow calorimeter is used to measure the specific heat of a liquid. Heat is added at a known rate to a stream of the liquid as it passes through the calorimeter at a known rate. Then a measurement of the resulting temperaturedifference betweenthe inflow and theoutflow pointsof the liquid stream enables us tocompute thespecific heat of the liquid. A liquid of density 0.2 g/cm3 flows through a calorimeterat the rate of10 cm3/s. Heat is added by means of a 250-W electric heating coil,anda temperaturedifference of 25C is establishedin steady-stateconditionsbetween the inflow and the outflow points. Find the specific heat of the liquid. ^BansalClassesColorimetry& HeatTransfer[8J Q.8Toluene liquid of volume 300 cm3 at 0C is contained in a beaker an another quantity of toluene of volume 110 cm3 at 100C is in another beaker. (The combined volume is 410 cm3). Determine the total volume of the mixture of the toluene liquids when they are mixed together. Given the coefficient of volume expansion y = 0.001/C and all forms of heat losses can be ignored. Also find thefinal temperature of the mixture. Q.9Ice at -20C is filled upto height h = 10 cm in a uniform cylindrical vessel. Water at temperature 9C is filledin another identical vessel upto the same height h= 10 cm.Now, water from second vessel is pouredintofirstvesselanditisfoundthatlevelofuppersurfacefallsthrough Ah = 0. 5 cm when thermal equilibrium is reached. Neglecting thermal capacity of vessels, change in density of water due to change in temperature and loss of heat due to radiation, calculate initial temperature 0 of water. Gi ven,Density of water,pw =1gm cm-3 Density of ice,p.=0.9gm/cm3 Specific heat of water,sw =1 cal/gm C Specific heatof ice,s; =0.5 cal/gmC Specific latent heatof ice,L = 80 cal/gm Q.10A composite body consists of two rectangular plates of the same dimensions but different thermal conductivities KA and Kg. This body is used to transfer heat between twoobjects maintainedat different temperatures. The composite body can be placed such that flow of heat takes place either parallel to the interface or perpendicular to it. Calculate the effective thermal conductivities Kn and K^of the composite body for the parallel and perpendicular orientations. Which orientation will have more thermalconductivity? Q.llTwo identical thermally insulated vessels, each containing n mole of an ideal monatomic gas, are interconnectedbya rodof length I andcross-sectionalarea A.Materialof therodhas thermal conductivity K and its lateral surface is thermally insulated.If, at initial moment (t = 0), temperature of gas in two vessels is T, and T2 (< T,), neglecting thermal capacity of the rod, calculate difference between temperatureof gas in two vessels as a function of time. Q. 12A highly conductingsolidcylinder of radius a and length I is surroundedby a co-axial layer of a material having thermal conductivity K and negligible heat capacity.Temperature of surrounding space (outside the layer) is T0, which is higher than temperature of the cylinder.If heat capacity per unit volume of cylinder material is s and outer radius of the layer is b, calculate time required to increase temperature of the cylinder from T, to T,. Assume end faces to be thermally insulated. Q.13A vertical brickduct(tube) is filled with cast iron.The lowerendof theduct is maintainedat a temperature Tj which is greater than the melting point Tm of cast iron and the upper end at a temperature T2 which is less than the temperature of the melting point of cast iron. It is given that the conductivity of liquid cast iron isequal to k times the conductivity of solid cast iron. Determine the fraction of the duct filledwith molten metal. Q.14Water is filled in a non-conductingcylindricalvesselof uniform cross-sectionalarea.Heightof water column is hQ and temperature is 0C. If the vessel is exposed to an atmosphere having constant temperature of-0C (< 0C) at t = 0, calculate total height h of the column at time t. Assume thermal conductivity of ice to be equal to K.Density of water is pai and that of ice is p.. Latent heat of fusion of ice isL. IiBansal ClassesCalorimetry& HeatTransfer14] Q.15A lagged stick of cross section area 1cm2 and length 1 m is initially at a temperature of 0C. It is then kept between 2 reservoirs of tempeature 100C and 0C. Specific heat capacity is 10 J/kgC and linear mass density is 2 kg/m. Find 100C- oC X (a)temperature gradientalong the rod in steady state. (b)total heat absorbed by the rod to reach steady state. Q. 16A cylindrical blockof length 0.4 m an areaof cross-section0.04m2 is placedcoaxiallyon a thin metal disc of mass 0.4 kg and of the same cross-section. The upper face of the cylinder is maintained at a constant temperatureof 400K and the initial temperatureof the disc is 300K. If the thermal conductivity of the material of the cylinder is 10 watt/m-K and the specific heat of the material of the disc in 600 J/kg-K, how long will it take for the temperature of the disc to increase to 350K? Assume, for purposes of calculation, the thermal conductivity of the disc to be very high and the system to be thermally insulated except for the upper face of the cylinder. Q.17A copper calorimeter of negligible thermal capacity is filled with a liquid. The mass of the liquid equals 250 gm. A heating element of negligible thermal capacity is immersed in the liquid. It is found that the temperature of the calorimeter and its contents rises from 25 C to 30C in 5 minutes when a or rent of 20.5 ampere is passed through it at potential difference of 5 volts. The liquid is thrown off and the heater is again switched on. It is now found that the temperature of the calorimeter alone is constantly maintained at 32C when the current through the heater is 7A at the potential difference 6 volts. Calculate the specific heat capacity ofthe liquid. The temperature of the surroundings is 25C. Q.18A solid copper sphere cools at the rate of 2.8 C per minute, when its temperature is 127C. Find the rate at which another solid copper sphere of twice the radius lose its temperature at 327C, if in both the cases, the room temperature is maintained at 27C. Q.19Acalorimetercontains100cm3ofaliquidofdensity0.88g/'cm3inwhichareimmerseda thermometer and a small heating coil. The effective water equivalent of calorimeter, thermometer andheatermay be takentobe13 gm.Currentof 2 A is passedthroughthe coil.The potential difference across the coil is 6.3 V and the ultimate steady state temperature is 55C. The current is increasedsothatthetemperaturerisesslightlyabove55C,andthenitisswitchedoff.Thr calorimeter and the content are found tocool at the rate of 3.6C/min. (a)Find the specific heat of the liquid. (b)The room temperatureduring the experiment was10C. If the room temperature rises to 26C, findthe current required to keep the liquid at 55C. You may assume that Newton's law is obeyed and the resistance of the heater remains constant. Q.20End A of a rod AB of length L = 0.5 m and of uniform cross-sectional area is maintained at some constant temperature.The heat conductivity of the rod is k =17 J/s-mK. The other end B of this rodis radiatingenergyinto vacuumandthe wavelength withmaximumenergydensityemitted fromthis end is X0 = 75000 A. If the emissivity of the end B is e =1, determine the temperature of the end A. Assumingthat except the ends, the rod is thermally insulated. Q.21A wire of length1.0 m and radius10"3 m is carrying a heavy currentand is assumed to radiate as a blackbody. At equilibrium temperature of wire is 900 K while that of the surroundings is 300 K. The resistivity of the material of the wire at 300 K is %2 x10"8 Q-m and its temperature coefficient of resistance is 7.8 x 10"3/C, Find the current in the wire, [a = 5.68 x10'8w/m2K4]. ^Bansal ClassesCalorimetry& HeatTransfer[13] Q.22The temperature distribution of solar radiation is more or less same as that of a black body whose maximum emission corresponds to the wavelength 0.483 pm. Find the rate of change of mass due to radiation.[Radius of Sun = 7.0 x108 m] Q.23A black plane surface at a constant high temperature Th, is parallel to another black plane surface at constant lower temperature T,. Between the plates is vacuum. In order to reduce the heat flow due to radiation, a heat shield consisting of two thin black plates, thermally isolated from each other, it placed between the warm and the cold surfaces and parallel to these. After some time stationary conditions are obtained. By what factor r\ is the stationary heat flow reduced due to the presence of the heat shield? Neglect end effects due to the finite size of the surfaces. Q.24The shell of a space station is a blackenedsphere in which a temperature T = 500K is maintained due tooperationofappliancesof thestation.Findthe temperatureof theshell if thestation is enveloped by a thin sphericalblack screen of nearly the same radius as the radius of the shell. Q.25A liquid takes 5 minutes to cool from 80C to 50C, How much time will it take to cool from 60C to 30C ? The temperature of surrounding is 20C. Use exact method. Q.26Find the temperature of equilibrium of a perfectly black disc exposed normally to the Sun's ray on thesurface of Earth.Imagine thatit has a nonconductingbackingso that itcan radiateonly to hemisphere of space. Assume temperature of surface of Sun = 6200 K, radius of sun = 6.9 x 108 m, distance between theSun and the Earth =1.5 xlo11 m. Stefan's constant = 5.7 xio~8 W/m2.K4. What will be the temperature if both sides of the disc are radiate? Blackened spl envelop IiBansal ClassesCalorimetry& HeatTransfer 14] EXERCISE-III Q.l Q.2 Q.3 The temperatureof100 gmof wateris tobe raisedfrom 24 C to90 C byaddingsteamto it. Calculate the mass of the steam required for this purpose.[JEE '96] Two metal cubes A & B of same size are arrangedas shown in figure. The extreme ends of the combinationare maintainedat the indicated temperatures. The arrangement is thermally insulated. The coefficients of thermalconductivityof A& Bare300 W/mCand200W/mC respectively. After steady state is reached the temperature T of the interface will be.[JEE 96] A double pane window usedfor insulatinga room thermally from outside consistsof two glass sheets each of area1m2 and thickness 0.01m separated by a 0.05m thick stagnant air space. In the steady state, the room glass interface and the glass outdoor interfaceare at constant temperatures of 27C and 0C respectively.Calculate the rate of heat flow through the window pane. Alsofind thetemperaturesofotherinterfaces.Giventhermalconductivitiesofglassandairas0.8and 0.08 W m'K-1respectively.[JEE' 97] AB o oU oo T Q.4 The apparatus shown in the figure consists of four glass columns connectedbyhorizontalsections.Theheightoftwocentral columns B & C are 49 cm each. The two outer columns A & D areopentotheatmosphere.A&Caremaintainedata temperature of 95 C while the columns B & D are maintained at 5C. The height of the liquid in A & D measured from the base line are 52.8 cm & 51 cm respectively. Determine the coefficient of thermal expansion of the liquid.[JEE '97] A 95< C 95 Q.5 Q.6 Q-7 Q.8 A spherical black body with a radius of 12 cm radiates 450 W power at 500 K.If theradius were halved and the temperature doubled, the power radiated in watt would be : (A)225(B)450(C)900(D)1800 Earth receives1400 W/m2 of solar power. If all the solar energy falling on a lens of area 0.2 m2 is focussed on toa blockof ice of mass 280 grams,the time taken tomelt the ice will be minutes.(Latent heat of fusion of ice = 3.3 x105 J/kg)[JEE '97] A solid body X of heat capacity C is kept in an atmospherewhose temperature is TA = 300K. At time t = 0, the temperature of X is T0 =400K. It cools according to Newton's law of cooling. At time tj its temperature is found to be 350K. At this time tpthe body X is connected to a larger body Y at atmospheric temperature TA, througha conductingrodof length L,cross-sectionalarea A and thermal conductivity K. The heat capacity of Y is so large that any variation in its temperature may beneglected.Thecross-sectionalareaAof theconnectingrodissmallcomparedtothe surface area of X. Find the temperatureof X at time t = 3tr[JEE'98] A black body is at a temperature of2880 K. The energy of radiation emitted by this object with wavelength between 499 nm and 500 nm is Upbetween 999 nm and 1000 nm is U2 and between1499 nm and 1500 nm is U3. The Wien constant b = 2.88 x lO6 nm K. Then[JEE' 98] (A)Uj = 0(B)U3 = 0(C)U,>U2(D)U2>U1 l|BansalClassesCalorimetry& HeatTransfer[12] Q.15A bimetallic strip is formed out of two identical strips one of copper and the other of brass. The coefficient of linear expansion of the two metals are ac and aB. On heating, the temperature of the strip goes up by AT and the strip bends to form an arc of radius of curvature R. Then R is: (A) proportionalat AT(B) inversely proportional to AT[JEE'99] (C) proportional tojotg -ac (D) inversely proportional to|aB -ac Q.10A block of ice at -10C is slowly heated and converted to steam at100C. Which of the following curves represents the phenomenon qualitatively?[JEE (Scr) 2000] (A)(B)|( Q| Heatsupplied Heatsupplied (D) HeatsuppliedHeatsupplied Q. 11The plotsof intensity versus wavelength for three black bodies at temperatureTj,T,andT3respectivelyareasshown.Their temperatures are such that[JEE (Scr) 2000] (A)Tj>T2>T3(B)T1>T3>T, (C) T2 > T3 > Tx(C) T3 > T2 > Tj Q. 12Three rods madeof the same materialand having the samecross-section have bnen joined as shown in the figure. Each rod is of the same length. The left and right ends are kept at 0C and 90C respectively. The temperature of the junction of the three rods will be[JEE(Scr)2001 ] (A) 45C(B) 60C(C) 30C(D) 20C oc-/90C -90CC Q.13An ideal black body at room temperature is thrown into a furnace. It is observed that (A) initially it is the darkest body and at later times the brightest. (B) it the darkest body at all times (C) it cannot be distinguishedat all times. (D) initially it is the darkest body and at later times it cannot be distinguished.[JEE(Scr)2002] Q. 14An ice cube of mass 0.1 kg at 0C is placed in an isolated container which is at 227C. The specific heatS of thecontainervaries withtemperatureT accordingtheempiricalrelations= A + BT, where A=100 cai/kg-K and B = 2 x 10'2 cal/kg-K2. If the final temperature ofthe container is 27C, determine the mass of the container. (Latent heat of fusion for water = 8 x 104 cal/kg. Specific heat of water = 103 cal/kg-K)[JEE' 2001] Q.15Two rods one of aluminium of length /, having coefficient of linear expansion aa, and other steel of length l2 having coefficient of linear expansion as are joined end to end. The expansion in both the h rods is same on variation of temperature.Then the value of^+^is[JEE1 (Scr) 2003] (A) aa+ as (B) a . aa- as (C) aa+ as a . (D) None of these ^BansalClassesCalorimetry& HeatTransfer[13] Q.15 Q.17 Q.21 2 kg ice at -20C is mixed with 5 kg water at 20C. Then final amount of water in the mixture would be; Given specific heat of ice = 0.5cal/gC, specific heat of water = 1cal/gC, Q.18 (a) (b) Q.19 Latent heat of fusion of ice = 80 cal/g. (A) 6 kg(B) 5 kg(C) 4 kg If emissivity of bodies X and Y are ex and ey and absorptive power are Ax and Ay then[JEE* (Scr) 2003] (A)ey>ex; Ay>Ax(B)ey K,K, =a2b, K1= Q.l1 : 1.26 Q.69.02x105 gm Q.945C ka +kB Q.12 -loge-loge 2KUyvto ~t2 ; Q.14 h0+ C\ N_PL] 2kfit \ Pi Lf Q.15 Q.1721000Jkg-'K-1 Q.18 Q.20 TA-423 K Q.21 Q.23n=3 Q.24 Q.2510 minutes Q.26 I 1 _ Q 1 1(T,-T2)e k ^ - T J ( 4KAts| 3nRi J Q-13I^ - Tm )+( T ^ ) Q.19(a)0.42 cal/gmC,(b) 1.6A dm Q.22=5.06x109kg/s Q.l12 gmQ.260C Q.42xl O^ CQ.5DQ.65.5 min EXERCISE-III Q.341.53 Watt; 26.48C;0.55C l0ge 2 Q.7k= ;T = 300 + 50 exp. KA+loge2 2ti LCtj Q.8DQ.9B, DQ.10AQ.llBQ.12BQ.13D Q.15AQ.16AQ.17AQ.18(a) 595 watt/m2,( b) T0420K K Q.20DQ.21CQ.22y,= 2asQ.234 e a L T3+ Ks Q.25CQ.26AQ.27AQ.28B ^BansalClassesCalorimetry & Heat Transfer Q.140.5 kg Q.19B Q.24A :c; BANSALCLASSES TARGETIITJEE2007 XI(PQRS) QUESTION BANKON caloMIMmMM^^EAT TRANSFER TimeLimit:2SittingEachof90 minutes,durationapprox. Distrancefrom hotend ObjectiveQuestion BankOnHeat Thereare 58questionsinthisquestionbank. Q. 1The ends of a long bar are maintained at different temperatures and there is no loss of heat from the sides of the bar due to conduction orI g radiation. The graph of temperature against distance of the bar when it| has attained steady state is shown here. The graph shows (A) the temperature gradient is not constant (B) the bar has uniform cross-sectional area (C) the cross-sectional area of the bar increases as thedistance from the hot end increases (D) the cross-sectional area of the bar decreases as the distance from the hot end increases. Q.2One end of a 2.35m long and 2.0cmradius aluminium rod (K-235 W.m'Kf1) is held at 20C. The other end of the rod is in contact with a block of ice at its melting point. The rate in kg. s_1 at which ice melts is (A) 48tix10"6(B) 24TI xlCT6(C) 2.471x10"6(D) 4.87c x 10"6 10 [Take latent heat of fusion for ice as xl05J.kg'] Q.3The power radiated by a black body is P and it radiates maximum energy around the wavelength X0. If the temperature of the black body is now changed so that it radiates maximum energy around wavelength 3/4X0> the power radiated by it will increase by a factor of (A) 4/3(B) 16/9(C) 64/27(D) 256/81 Q.4A rod of length L with sides frilly insulated is of a material whose thermal conductivity varies with a temperature as K= ^ ,where ais a constant. The ends of the rod are kept at temperature T1 and Tr The temperatureT at x, where x is the distance from the end whose temperature is T; is X (A)T, (To V_ .x; T2^_^.T> -T. 12 VT\j (B)(C)TleTlLCD) T, Q. 5Equal masses of three liquids AB and C have temperatures10C, 25C and 40C respectively. If A and B are mixed, the mixture has a temperature of 15C. If B and C are mixed, the mixture has a temperature of 30C,. If A and C are mixed the mixture will have a temperature of (A)16C-(B) 20C(C) 25C(D)29C Q.6A volume of 120 ml of drink (half alcohol + half water by mass) originally at a temperature of 25 C is cooled by adding 20 gm ice at 0C. If all the ice melts, the final temperature of the drink is: (density of drink = 0.83 3 gm/cc, specific heat of alcohol = 0.6 cal/gm/0C) (A) 4C(B) 5C(C)0C(D) 6C Q.7Aclockpendulummadeofinvarhasaperiodof0.5 secat20C. Iftheclockisusedinaclimatewhereaverage temperature is 30C, approximately how much fast or slow will the clock run in 106 sec. [ainvar=lxlO^/C] (A) 5 sec fast(B) 10 sec fast(C) 10 sec slow(D) 5 sec slow Q.8An aluminium container of mass 100 gm contains 200 gm of ice at -20C. Heat is added to the system at the rate of 100 cal/s. The temperature of the system after 4 minutes will be (specific heat ofice = 0.5 and L= 80 cal/gm, specific heat of A/=0.2 cal/gm/C) (A)40.5C(B) 25.5C(C)30.3C(D)35.0C Q.9A black metal foil is warmed by radiation from a small sphere at temperature' T1 and at a distance' d' . It is found that the power received by the foil is P. If both the temperature and distance are doubled, the power received by the foil will be: (A)16 P(B)4 P(C)2 P(D)P faBansalClassesQuestionBankOn Calorimetry& HeatTransfer[2] Q. 10Asteel tape gives correct measurement at 20C. Apiece ofwood is being measured with the steel tape at 0C. The reading is 25 cm on the tape, the real length of the given piece ofwood must be: (A) 25 cm(B) 25cm(D) cannot say Q.llA rod of length 20 cm is made of metal. It expands by 0.075 cm when its temperature is raised from 0C to100C. Another rod of a different metal B having the same length expands by 0.045 cm for the same change in temperature, a third rod of the same length is composedof two parts one of metal A and the other of metal B. Thus rod expand by 0.06 cm.for the same change in temperature. The portion made of metal A has the length: (A) 20 cm(B) 10 cm(C)15cm(D)18cm Q.12A crystal has a coefficient of expansion 13 x 10~9 in one direction and 231 x i0~9in every direction at right angles to it. Then the cubical coefficient of expansion is: (A) 4.62 x10"7(B) 2.44x 10~7(C) 4.75x 10"7(D) 2.57 xl0"7s Q.13Star S j emits maximum radiation of wavelength 420 nm and the star S2 emits maximum radiation of wavelength 560 nm, what is the ratio of the temperature of S, and S2: (A) 4/3(B) (4/3 )1/4(C) 3/4(D)(3/4)1/2 Q.14If 1gm water requires x heat to boil to steam at 100C, and 1 gm water requires>> heat to evaporate completely at 0C, then (A)x>y(B)x =y(C)x -\ faBansalClassesQuestion BankOn Calorimetry& HeatTransfer[2] BANSALCLASSES CHEMISTRY TARGETIITJEE2007 XI (P,Q,R,S) CHEMICALCLASSIFICATION & PERIODICITYINPROPERTIES (S&PBLOCK) Knowledgewhen not"Classified" orassorted properlyisasuselessasabooknotplaced accordingtotheorderin aHugelibrary. CONTENTS txttctstt txttctsttt +srttrt: PERIODICITY Along a Period () Along a Group( J) * Max.Z Constant Max. Z* (effective due to screening) rn (atomic, ionic radius). Cationsmallerthanatom,anionlargerthanatom (I P.) c Fe, Co, Ni havesize,also Zr,Hf Be >B, N> O,inertgas max,Ij F. S >O, P > N (Hydration and HydrationEnergy) (Size of Hydrated ion) (forcations) (Polarising Power of cation)NaF " (Basic nature of oxides) (Reactivity) (Reducing Nature) Isoelectric ions have different size. Inert pair effect is in p-block. Stability of higher state decreases and that of lower state increases going along a group. Ge2+ < Sn2+ < Pb2+ Reducing nature of hydride increases in a group and decreases in a period. (!jBansalClassesChemical Classification& Periodicity in Properties(s & p block)[9] Part-A(Periodic Table) INTRODUCTION: Many attempts were made to classify the known elements from time to time. These are: (i) Proust Hypothesis(ii) DoberniersTriadlaw(iii) Newlands Octave law (iv) Lother Meyer's curve(v) Mendeleev Periodic law(vi) Modern periodic law PERIODICLAW(1869): The physical and chemical properties of elements are periodic functions of their atomic weight. MODERNPERIODICLAW: The physical and chemical properties of elements are periodic functions of their atomic number. LONGFORMOFPERIODICTABLE: [BOHR'STABLE] basedonmodernperiodiclaw and Bohr Burry Scheme of E.C. CLASSIFICATION OF ELEMENT INTO GROUPS AND PERIODS : Group A:s and p block elements, representative elements. IA to VII A andO group. Group B :d and f block elements, transition and inner transition elements IB to VIIB and VIII groups. Total16 Groups Period1 to 7 classified as short, shortest, long, longest and incomplete period. CLASSIFICATIONOFELEMENTSINTOs,p,d & fBLOCKELEMENTS : s -blockJ (i)configurationns1 - 2(ii)laste~enters ins orbital (iii)two groupsIA or1;IIAor2 p -block: (i)configurationns2n p1 - 6(ii)laste~enters inp orbital (iii)sixgroupsIII A,IVA, VA,VI A, VII A,zeroor13,14,15,16,17,18 d -block:[ TransitionElements ] (i)configurationns1 "2( n-1)d1 ~10(ii)laste~enters ind orbital (iii)their two outermost shell are incomplete (iv)10 groupsIII B , IVB, VB, VI B,VII B , VIII (Triad), I B, IIBor 3 , 4 , 5 , 6 , 7 , ( 8 , 9 , 1 0 ) , 1 1 , 1 2. (v)four series3 d , 4 d , 5 d , 6 d. f - bl ock:[InnerTransition] (i)configurationns 2(n-1) d0-1( n-2 ) f1-14 (ii)laste~entersinforbital (iii)two series4 f Lanthanides&5 fActinides ESTIMATING POSITION OF AN ELEMENT FROM ITS ELECTRONICCONFIGURATION: The last electron enters which subshell gives idea of its block. Think:1s1 and1 s2 belongs to which block] Period no. is equal to the valence shell present in the configuration. Also for s and p block elements. Period no. = valence shell, for' d' block = shell +1,for fblock = shell + 2 and so on. Group no. for s and p block = valence shell electron (A) for d block = dl to d5 [no. of (s + d) electron (B)] d6, d7, d8(VIII) s1 d9, d10 (IB, IIB) [ Use these carefully while locating the position.] (!jBansalClassesChemical Classification& Periodicity in Properties (s & pblock)[9] COMMONLY ASKEDPROPERTIES: 1.AtomicVolume:Volume occupied by one gm atom of an element. ,Atomicweight Atomic volume = density Loweratomic volumeleadstohigherdensity, increasedhardnesshighermelting point, boiling point, less malleability & ductility. 2.AtomicRadius: Problem in calculating actualsize of atomand hence distance between nuclei is calculated giving rise to three type of radii for atoms. d (a)Covalentradius:fCr =^Cr< actual atom size [Slight difference] [Used for H^Cl2 and such molecules] d (b)MetallicRadius: [Used for metals] d Mr =Mr > actual size [Slight difference] (c)Vandenvaalradius: ( T^^ P)Vr =Vractual size [very large difference] In general VR > Mr > CR (d)Ionic Radius:A cation is smaller than parent atom. An anion is larger than parent atom. FACTORS AFFECTING ATOMIC SIZE : (a)'n' increase size increases (b)Zeffincrease size decrease[ Ze f f- Z- a] (c)Type of measurement of radii. Calculation of Zeff Jgn2Exn2 where E is I.E. inkJ/mole;Zff=JE is I.E. in eV per atom. 1312eflV13.6 orCalculated by Slaters rule. SLATER'SRULE: (a)For calculating aon a (s or p) block (other than on 1 s) Rule-1 : Each (ns, nP) electron contribute to a screening factor of 0.3 5. Rule-2 : Each (n -1 )th shell electron contribute to a screening factor of 0.85. Rule-3 : Each (n -2)nd and deeper shell electron contribute to a screening factor of 1. [*On 1 s, the screening factor due to other electron is taken as 0.3 ] (b)For calculating aon (d or f) bl ock. Rule-1 : Each screening causing electron (d and f only) of same shell has factor of 0.3 5. Rule-2 : Each electron other than Rule-1have screening factor of 1. GeneralTrend: Along a period, size decrease ['n'constant, ZeffT ] Along a group, size increase ['n' increasing, Zeff constant] Exceptions: (1)Noble gases have largest atomic sizes [Vander waal radii]. However, their covalent radii are smaller e.g. Xe. (2)Size of Ga and A1 are same, [Zeff increasing] (!jBansalClassesChemical Classification& Periodicityin Properties(s & p block) [9] ATOMICRADIUS ALKALI METALSALKALINE EARTH METALSGROUPffl-A s,2.35 1.8 1 , 2 . 2 2 1 . 61.4 1.2 ?1 So.s 0.6 0.4 0.2 0 itl1-M.-TS174 LiNaKRbCs CARBONFAMILY BeMgCaSrAlGaInH NITROGEN FAMILY (PNICOGENS) 2 CSiGeSnPb CHALCOGENS NPbAsSbBi HALOGENS can you predict or say about the increment in size along a group and decrement along a period] ISOELECTRONICSPECIES[Size depends upon Z, more Z less size]: (i)S2 -,C1" , K+,Ca2 +,Sc2 +(ii)S03,N03 ~ ,C032 ",COC^ (iii)N2,CO,CN -(iv) (vi) radiusofcation_Zeffof Anion (v)H-,He, Li + (vii)NCS " ,CS2 NH3,H3O + CH4,NH4 + (viii) radiusofanionZeffof Cation [Check out for size for an isoelectronic noble gas. ] IONISATIONENERGY: Amount of energy required to remove the most loosely bounded electron from an isolated gaseous atom. Units : kJ mol-1, k cal mol-1, eV per atom. Ionisation is endothermic (endoergic) i.e. requires energy hence AH is +ve M + Energy (IEj) M+ + e-M>M+ + e~AH = IE, M+-M+2--> M+2 +e-M+3 + e-AH=IE2 AH = IE. IE3 > IE2 > IEj always FACTORS AFFECTING IONISATIONENERGY: (1)Atomic size: Varies inversely Screening effect: varies inversely Nuclear charge: varies directly (2) (3) (!jBansalClassesChemical Classification& Periodicityin Properties(s & p block)[9] (4)Sp Elect, config of outermost electron (half filled / fullyfilled) (5)Type of orbital involved in Ionisation: s > p > d > f. Half fillness and full fillness of inner orbitals. [affects d block and f block trends] General Trend: Along period I.E. increases [with some exception] [ZeffT] Along a group I.E. decrease [Zeff constant, n T ] Exception: (1)Along a period, half filled and fully filled have higher I.E. e.g.Be >Ba n d N>0 . (2)along a group, Ga > A1 PROPERTIES AFFECTED BY IONISATION ENERGY: (1)Metallic character (2)Tending to stay in which state A+1. A+2 or A+3 (3)Other properties based on (1) IONISATION ENERGY ALKALI METALSALKALINE EARTH METALSGROUP MI A 900 800 700 t r600 ~X2|500 s400 "300 200 100 0 MgBAlGaIn CARBON FAMILY ^11.2 Ml 8,1-> Bn 7.3Pb, 1A 1111 CSiGeSnPb CHALCOGENS 8.43 OSbSeTePo NITROGEN FAMILY (PNICOGENS) NPbAsSbBi HALOGENS ELECTRONAFFINITY: Amount of energy released when an electron is added to an isolated gaseous atom. Units: k J mol- 1,k Cal mol_1andeV per atom. Exothermic(exoergic). EAj is always released. 2ndE. A. is always energy required. The sum ofEA,&EA2is energy required. EAar:aZp f f.CIhasthehighestE.A. atomic sizeen (!jBansalClassesChemical Classification& Periodicity in Properties (s & pblock)[9] ELECTRON GAIN ENTHALPY: Whenexpressedin termsofenthalpychange(AH) thenitis termedas E.G.E.Rememberthat AH = -ve for exothermic change. For EA,, energy is releasedAHea,= -ve For EAj, onwards is required.'.AHEA2 = + ve EA, + EAj, energy is always required. FACTORS AFFECTING ELECTRON AFFINITY: (1)Atomic size:varies inversely (2)Nuclear change:varies directly (3)Sp E.C. of half filled and fully filled shells. General Trend: Along a period, electron affinity increases [with exception] as ZeffT. Along a group,electron affinity decreases after 3rd period. Between 2ndand 3rd period in p block electron affinity of 2nd period is lowering to high electron density. Exception: (1)A fully filled and half filled which have low values or even sometimes energy is required rather than getting released. (2)2nd period has lower value than 3rd owing to repulsion between electrons. E. A.VALUES FOR s ANDvBLOCK IA0 HHe - 72HAIDAIV AVAVIAv n A +20a LiBeBCNOFNe - 60 +240a - 23-1230-141- 322+30 NaMgAlSiPSCIAr - 53 +230a - 44-139- 74- 201-348 +35a KCaGaGeAsScBrKr - 48 +150a -40a -116- 77-195- 324 +40a RbSrInSnSbTe1Xe - 46 +160a -40a -121-101-190-295 +40a CsBaTlPbBiPoAtRn - 45 +50a - 50-101-101 -170a -270a +40a ELECTRO NEGATIVITY:[ Propertiesof an atom in a molecule] Fhas highest.Decreasing order-F > O > CI = N > Br > S = C > I > H. PaulingScale: XA-XB =0.208 VaEinkcal/mol ^=^ A -B~O^ A -AX^ B-B)1'2 MuIIiken'sScale : XA=*p \E a(ev). Mulliken's values of ENare about 2.8 times as large as Pauling. ftI SQ7 Allred-Rochows: XA=, =3+ 0.744 r Sanderson:XA=0.21XA+0.77 (!jBansalClassesChemical Classification& Periodicity in Properties(s & p block) [9] PaulingSanderson Anion is less electronegative than parent atom. FACTOR AFFECTING ELECTRO NEGATIVITY: (1)Nuclearattraction:varies directly (2)Atomicradius:varies inversely (3)Change on ions: More positive charge more electronegativity and more -ve change less electronegativity. (4)Hybridisation:to be discussed later in bonding. General Trends: Along a period, electronegativity increases Along a group, electronegativity decreases Exceptions:None noteworthy. FACTORS DEPENDENT ON ELECTRO NEGATIVITY: (1)% ionic character varies directly. (2)Strength of bond varies directly. (3)B.L.: varies inversely. (4)Nature of hydrides (5)Nature of hydroxide. ELECTRONEGATIVITY ALKALI METALSALKALINE EARTH METALSGROUP HI A CARBON FAMILY i0.5 0 -I1i1-i CS iG eS nP bCHALCOGENS NITROGEN FAMILY (PNICOGENS) i 0.5 01111 NP bA sS bB iHALOGENS (!jBansalClassesChemical Classification& Periodicity in Properties(s & pblock)[9] OSbSeTePoFCIBrI MISCELLANEOUS CHEMICAL PROPERTIES: 1.Periodicity ofhydra acids : (a)Acidic character of hydra acid increases from left to right in a period. (b) Acidic character of hydra acid increases from top to bottom in a group. 2.Periodicity of oxy acids : (a)Acidic character of oxy acid increases from left in a period. (b) Acidic character of oxy acid decreases from top to bottom in a group. 3.Periodicity of natureof oxide : (a) On moving from left to right in a period acidic nature of oxide generally increases. e.g.C02< P203< S02< C102 (b) On moving from top to bottom in a groupacidic nature of oxide generally decreases. 4.Solubilityof salt inwater : (a) Hydration energy decreases along a group. (b) Lattice energy decreases along a group. TRENDSIN PHYSICAL PROPERTIES: Physical properties are mostly dependent on. Atomic weight and so not regular trend. Mark out exception in the graph and think out of the reasons? DENSITY ALKALI METALSALKALINE EARTH METALS (!jBansalClassesChemical Classification& Periodicity in Properties(s & p block) [9] ALKALI METALS MELTING POINT ALKALINE EARTH METALSGROUP EQ A aa la, 714 BeMgSrBaBAlOaInTl CARBONFAMILYPNICOGENS CHALCOGENSHALOGENS BOILING POINT ALKALI METALSALKALINE EARTH METALSGROUP i n A CARBON FAMILYPNICOGENS (!jBansalClassesChemical Classification& Periodicity in Properties(s & pblock)[9] CHALCOGENSHALOGENS SOME POINTS TOREMEMBER: 1.Second most electronegative element-Oxygen 2.Hydrogen is the lightest element and Lithium is lightest metal. 3.Helium has the highest value of I.P. 4.Fr has minimum value of electronegativity and ionisation potential. 5.In periodic table metalloids are only in p-block. 6.According to CAS system (chemical abstract system) total no. of groups are 16. 7.Total gaseous elements are 11(He, Ne, Ar, Kr, Xe, Rn, H2, N2, 02, Cl2, F2) 8.Liquid metal is - Hg. 9.Diamond is hardest natural substance. 10.Francium has the highest atomic volume. 11.Halogens have highest electron affinity and in that to CI has the highest amongst them. 12.The largest cation of the periodic table = Cs+. 13.The smallestcation of the periodic table = H+. 14.The largest anion of the periodic table = I". 15.The smallest anion of the periodic table = H~. 16.The biggest element of periodic table = Fr. 17.The smallest element of periodic table = H. 18.Br liquid non-metal. 19.Osmium heaviest element known. 20.Flourine is the most electronegative element. SOME COMMONLY USED TERMS : 1.Noble Gases: Element of group 18 are called noble gases. These are also called as inert gases because their outermost ns and np orbitals are compl etely filled (except He and 1 s2) and these gaseous are non-reactive in nature under ordinary conditions. 2.Representative elements: All the s and p block elements are known as representative elements except zero group. 3.Transition elements : All the d-block elements (except IIB group) are called transition element. It comprises into 4th, 5th, 6th and 7th period. They lie between s and p block elements. 4.Innertransitionelements: All the f-block elements or 4f and 5f blockelements are called inner transition element. Total number of these elements is 28. They lie in IIIB and placed at the bottom of periodic table. (!jBansalClassesChemical Classification& Periodicity in Properties(s & pblock)[9] 5.Typical elements:Elements second and third period are known as typical elements. 6.Diagonal relationship:Properties of elements of second period resemble with the element of third period. These resembled properties between two periods or this type of relation between two periods are called diagonal relationship. IAIIAIDAIVAVAVIAVIIA 2nd periodLiBeBCNOF XX X XX X 3rd periodBaMgAlSiPSCI Increase your I bank (i)Resemblance between Li and Mg : (a)Unlike the other members of the group, lithium reacts with N2 to form a nitride in the same way as magnesium does. (b)Lithium hydroxide, carbonate and nitrate decomposes on heating to give Li20 as like Mg but other alkali hydroxides and carbonates are unchanged on heating where as the nitrate decompose to give nitrite. (c)Lithium hydroxide carbonate and fluoride are much soluble than the corresponding sodium or potassium compounds. The solubilities are comparable to those of corresponding magnesium compound. (ii)Resemblance between Be and Al: (a)The ionic radius of Be2+ is nearly same as that for the Al3+. (b)Like aluminium, beryllium is not readily attacked by acids because of the pressure of an oxidefilm. (c)Beryllium dissolved in alkali to give the beryllate ion [B (OH)J2~ just as aluminium does to give (Al(OH)6)3~ (d)The oxides BeO and A^Og are hard high melting insoluble solids. The oxides as well as their hydroxides amphoteric and dissolve in sodium hydroxide solution. (e)Beryllium and aluminium from fluoro complex anion, BeF42~ and A1F63~ in solution, the other group II metals do not form stable fluoro complexes in solution. (f)BerylHum chloride (BeCl2) is essentially covalent and has a bridged polymeric structure just as aluminium trichloride is covalent forming a bridged dimer, A12C!6. B oth the chlorides are soluble in organic solvent and are strong Lewis acid. (iii)Resemblance between B andSi: (a)Boron and silicon form numerous hydride which spontaneously catch fire on exposure to air and are easily hydrolysed. (b)Boron halide like silicon halides hydrolysed by water. Aluminium halides are only partially hydrolysed by water. (c)Boron forms binary compounds with several metals known as borides just as silicon forms metal silicides some ofthe borides and silicides under go hydrolysis to yield boron and silicon respectively. (d)B203 and Si02 are acidic in nature, Borates and silicates have tetrahedral B04 and Si04 structural units respectively. Boro silicates are known in which form can replace silicon in three dimensional lattice. However boron can also form planer B03 unit. (e)Both B and Al are semiconductors. Bridge Elements:Typical elements of III period. NOMENCLATURE OFTHEELEMENT: The names are derived by using roots for the three digits in the atomic number of the element and adding the ending -ium. The roots for the number are (!jBansalClassesChemical Classification& Periodicity in Properties(s & pblock)[9] EXERCISE#I General Infoabout periodic table Q. 1Which of the following does not reflect the periodicity of element (A) Bonding behaviour(B) Electronegativity(C) Ionisation potential(D) Neutron/ Proton ratio Q.2Choose the s-block element in the following: (A)Is2, 2s2, 2p6, 3s2, 3p6, 3d5, 4s1(B)Is2, 2s2, 2p6, 3s2, 3p6, 3d10, 4s1 (C)1 s2, 2s2, 2p6, 3 s2, 3p6, 4s1(D) all ofthe above Q. 3False statement for periodic classification of elements is (A) The properties of the elements are periodic function of their atomic numbers. (B) No. of non-metallic elements is less than the no. of metallic elements. (C) First ionization energy of elements is not change continuously with increasing of atomic no. in a period. (D) d-subshell is filled by final electron with increasing atomic no. of inner transition elements. Q.4Pick out the isoelectronic structure from the following: I. +CH3II. H30+III. NH3IV.CHJ (A) I and II(B) III and IV(C) I and III(D) II, III and IV Q.5Based on location in P.T., which of the following would you expect to be acidic & which basic, (a) CsOH(b)IOH(c)Sr(OH)2(d) Se03(0H)2(e)FrOH(f)BrOH Q. 6Which of the ions are paramagnetic Sr2+, Fe3+, Co2+,S2~, Pb2+ Q.7If there were 10 periods in the periodic table then how many elements would this period can maximum comprise of. Q.8If (n +1) for energy rule is not followed, what are the blocks of the following elements. (a)K(19)(b) Fe(26)(c)Ga(31)(d)Sn(50) Q. 9Use the following system of naming elements in which first alphabets of the digits are written collectively, 0 1 2 3 4 5 6 7 8 9 nilurdbitriquadpenthexseptoctenn to write three-letter symbols for the elements with atomic number 101to 109. [Example: 101 isUnu....] Q.10A student is given samples of three elements, X, Y and Z, which could be an alkali metal, a member of group IV Aand a member of group VA. She makes the following observations: Element X has a metallic lusture and conducts electricity. It reacts slowly with aq HCl to produce H9. Element Yis a light-yellow solid and does not conduct electricity Element Z has a metallic lusture and conducts electricity. When exposed to air, it forms a white powder aqueous solution of which is basic. What can you conclude about the elements from these observations? Properties and Periodic trends Q.llThe size of the following species increases in the order: (A) Mg2+ < Na+ < F" < Al(B) F" < Al < Na+ < Mg2+ (C) Al < Mg < F" < Na+(D) Na+ < Al < F" < Mg2+ Q.12Element in which maximum ionization energy of following electronic configuration would be (A) [Ne] 3s2 3P1(B) [Ne] 3s2 3p2'(C) [Ne] 3s2 3p3(D) [Ar] 3d10 4s2 4p3 Q.13The outermost electronic configuration of most electronegative element is: (A) ns2 np(B) ns2np4(C)ns2np5(D)ns2np5 feBansalClassesChemical Classification dt Periodicity in Properties (s & pblock)[17] Q.14The electron affinity of the members of oxygen of the periodic table, follows the sequence (A) O > S > Se(B) S > O > Se( C) S>Se >0( D) Se >0>S Q.15The process of requiring absorption of energy is (A) F - F~(B) CI CI""( C) 0- - >02"(D) H > H~ Q.16In the following which configuration of element has maximum electronegativity. (A)Is2, 2s2 2p5(B)Is2, 2s2 2p6(C)Is2, 2s2 2p4(D)Is2, 2s2 2p6,3s23p3 Q.17Highest size will be of (A) Br(B)I(C)I-(D)I+ Q.18Atomic radii of flourine and neon in A units are respectively given by (A) 0.72,1.60(B) 1.60,1.60(C) 0.72, 0.72(D) none of these Q.19The correct order of second ionisation potential of C, N, O and F is: (A) C>N>O >F(B) O >N>F>C( C) 0 > F > N> C( D) F >