Please answer T (True) or F (False) to the questions 1 - 10. (2% each, 20% total)

I 1. The 3s- and 3d-orbitals of a H atom are degenerate.

2. The three 0 atoms in a O3 molecule have the same electronegativity. So O3 is a nonpolar

molecule.

3. For nitrogen gas at room temperature, one N2 molecule has two rotational modes of motion and

average rotational energy of kT.

4. Thermodynamically unstable compounds have positive AGfO, and they always decompose very

fast.

5. When heating liquid water in a laboratory, zeolite is often used to prevent superheating and flash

boiling. The main reason is that the dissociation of zeolite raises the boiling point of water.

6. In the reaction, C 0 2 + H20 + H2CO3 , the C atom of C02 is a Lewis acid.

7. The cell, Pt I H2(g) I :HCl(aq) I Hg2C12(s) ( Hg(l), is a complete electrochemical cell and workable

without a salt bridge.

8. The hardness of water is based on the amount of M ~ ~ + and Kt ions in it.

1 9. The acidity of dichloroacetic acid is higher than of acetic acid.

10. A protein's primary structure is defined as the local conformation of its polypeptide backbone. I

Example: a helix; p sheet.

Choose a correct answer for each of the questions 11 - 30. (3% each, 60% total) I

11. For a one-dimensional particle in a box, which of the following statements is true?

I A) The lowest possible energy is 0.

I B) For n = 1, the wavelength is equal to the length of the box.

C) The probability of finding the particle in a region is proportional to the value of

1 wavefunction y.

I D) As the mass of the particle becomes heavier, the separation between neighboring energy levels decreases.

12. Which of the following has the smallest radius?

A) p3- B) Ar C) ca2+ D) K

13. Which of the following has the smallest bond angle?

A) XeF4 B) NH3 C) H20 D) C&

14. On the basis of molecular orbital theory, which of the following statements about 0 2 molecule in

ground state is not true?

A) bond order = 2

B) the highest occupied molecular orbital is the antibonding n2,* orbital

C) have an even number of electrons, and all electrons are paired

D) paramagnetic

15. Which of the following gases will have the largest root mean square speed at 100°C?

A) neon B) oxygen C) nitrogen D) carbon dioxide

16. Aluminum metal is crystallized in a cubic close-packed (ccp) structure. How many atoms are in a

unit cell?

A) 2 B) 4 C) 6 D) 8 17. In an adiabatic process, a system cannot exchange heat with its surroundings. Indicate which of

the following statements is always true about an adiabatic process in a closed system. (U: internal

energy; w: work; q: heat)

A) AU=O B) AT= 0 C) AU= w D) AU=q

18. Without any calculation, predict which of the following processes causes a decrease of entropy.

A) S02(g) + Br2(g) + 2 H20(1) + H2S04(aq) + 2 HBr(aq)

B) 2 HCl(aq) + CaC03(s) + CaC12(aq) + H20(1) + C02(g)

C) CuS04-5H20(~) + CuS04(s) + 5 H20(1)

D) 2 NH3(g) + N2(g) + 3 H2(g) 19. Two liquids A and B can be mixed and formed an ideal solution. That means:

A) the solution obeys Raoult's law.

B) the boiling temperature Tb of the solution is between Tb of pure A and of pure B.

C) azeotrope will never be found when distilling the solution.

D) all statements above are true.

20. 3 H2(g) + N2(g) + 2 NH3(g) is an exothermic reaction. Now there is a vessel containing NH3 , N2 , H2 gases in equilibrium. How to increase the amount of NH3 gas in the vessel?

A) Use Fe metal as a catalyst.

B) Increase the temperature.

C) Lower the temperature.

D) Add Ar gas to increase the pressure. 21. Choose the effective pH range of a acetic acid/sodium acetate buffer. For acetic acid, pK, = 4.74.

A) 1.4-3.4 B) 3.7-5.7 C) 5.9-7.9 D) 8.2-10.2

22. Ag+(aq) + e- + Ag(s) EO = +0.80 V

~ e " ( a ~ ) + 2 e + Fe(s) EO = -0.44 V

The standard potential of the cell, Fe(s) I ~ e " ( a ~ ) 11 Ag+(aq) IAg(s), is:

A) +1.24 V B) -2.04 V C) +1.02V D) -1.24 V

23. The reaction, 2 NO(g) + 2 H2(g) + N2(g) + 2 H20(g), is first order in H2 and second order in

NO. Starting with equal concentration of H2 and NO, the rate after 20% of H2 has reacted is what

percent of the initial rate?

A) 80% B) 64% C) 51% D) 41%

24. The activation energies of reaction A and B are 30 and 100 kJ/mol respectively. Which of the

following statements is true?

A) Reaction A has a rate that is more sensitive to temperature than reaction B.

B) Reaction B has a rate that is more sensitive to temperature than reaction A.

C) Reaction A must be first order because of its low activation energy.

D) Reaction A must react faster than reaction B. 25. Chromium is an important element to our life. Which of the following statements about Cr is not

true?

A) One of the main components of the stainless steel.

B) cr3' : required in trace amounts by living organisms.

C) ~ r 2 0 7 ~ - : an oxidizing agent ; very toxic.

D) All of its oxides are acidic. 26. How many stereoisomers does [C~Cl~(en)~] ' have? (hint: en = ethylenediamine)

A) 1 B) 2 C) 3 D) 4 27. The complexes [ F ~ ( H ~ o ) ~ ] ~ ' and [F~(cN)~]~- have high- and low-spin electron configurations

respectively. So we know that:

A) the Fe ion in [F~(cN)~]~- has 2 unpaired d-electrons.

B) the Fe ion in [Fe(~20)6]~' has 4 unpaired d-electrons.

C) the C N ion is a weak-field ligand.

D) [ F ~ ( H ~ O ) ~ ] ~ ' has a larger ligand field splitting than [F~(cN)~]" . 28. Name the compound (CH3CH2)2CHCH=CHCH3.

A) diethylbutene

B) 4,4-diethyl-2-butene

C) 3-ethyl-4-hexene

D) 4-ethyl-2-hexene

29. Which of the following compound undergo nitration slower than benzene?

A) chlorobenzene

B) benzoic acid

C) phenol

D) aniline

I 30. What are the formulas of the monomers used to produce the PET shown below?

A) HOCH2CH20H and HOOC-C6&-COOH (substituents are para)

B) NH2CH2CH2NH2 and C100C-C6H4-COOCl (substituents are para)

C) HOOCCH2CH2COOH and Br-C6&-Br (substituents are para)

D) HOCH2CH2COOH and HO-C6&-COOH (substituents are para)

An Imstigation info the Relationship between Students' Conceptions ofthe PaI%cul&! Nature d Matier and their t.tnder~bWfin@ of Chemical &anding

181 Unau fiorraZ Jowt-aul of Scid-ttcc Edz4cr~ ti01t

V01. -70, dTa. If, 3 .Yept+'~~Eer 2008, fip. I5-7l-I5-_CI;I

A thorough understanding sf cheuimi bonding requires falililiarity with the particulate nature ef mrmr. In this study, a m~-tIer multiple-choice diagnostic i ~~~rrmmnt consistiiq cpf ten items (fire items involving each of the two concepts) was developed to assess students' understding af the p a d d a t e nawe of matter and chemical banding so as to identjfy possible asso&ticms between students' u n d m s m of the two concepts. ?he i n s m e l i t was aciminigrwed to 260 Grades Q a d 10 students (1.5-16 years old) from a secondary scbel in Singapore, Analysis of students' responses revealed several alternative conmptians abmt the two coixcpts. In addition, nnalgsis of six p a h of itenm suggested thar &B' limited mdmtancline ad the parridate nature of mawr d u e n d their- undersmndk of chemical hndktg. The findmgs provide usefid information for cheDenSiag students' dternative conceptinns about the pmialrte name of matter during dass- room insmerioa in order to ennbk them to achieve better un&mtan&ng of chemical bondk~.

Resmrcfi findines indicate that secondary sczlwol students generally experience diffi- c111q in understanding rhe cc?nceyt of chemical bonding. This study was undenslken In order to determine the extent to which sn~dents' lack of understanding of the nature and behwiour of particles infl~~eilces their understandiiq about chmnioal bonding. The specific resmi.cla questions far this study were: (1) What are students' erkcrnative conreprians about tile parriculatt. nature of matter? (2) !T%at are students' alternative conccptiolls akaut chemical bonding? 13) b7hnt is the colrelation between students' ~mderstsnding of the particulate nature of nzaner and chemical bonding?

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