2. Which if the following is the correct order of boiling points for KNO3, CH3OH, C2H6, Ne?A) Ne < CH3OH < C2H6 < KNO3

B) KNO3 < CH3OH < C2H6 < NeC) Ne < C2H6 < KNO3 < CH3OH D) Ne < C2H6 < CH3OH < KNO3

E) C2H6 < Ne < CH3OH < KNO3

3.Which of the following has the highest melting temperature?F) H2OG) CO2

H) S8

I) MgF2

J) P4

You need to determine the bond strength: the stronger the bond, the higher melting point or boiling point.KNO3, MgF2 – ionic compounds, so intermolecular bonding is the strongest among other molecules, hence higher melting and boing points.Rules: For ionic compounds: the bigger charge of ions, the stronger bond. if charges are the same – the smaller ion, the stronger bond For non-ionic compounds: depends on type of bonding (hydrogen>dipole-dipole> London dispersion) if type of bonding is the same – the bigger molecule, the stronger bond

4. A certain substance, X, has a triple-point temperature of 20 0C at a pressure of 2.0 atm. Which one of the statements cannot possibly be true? A) X can exist as a liquid above 20 0C.B) X can exist as a solid above 20 0C.C) Liquid X can exist as a stable phase at 25 0C, 1 atm.D) Both liquid and solid X have the same vapor pressure at 20 0C.

Possible two different phase diagrams

A) is always true, B) is true only for first picture, but still it is possibleD) is true only at pressure 2 atm, but still it is trueC) cannot be true, because triple-point determines the lowest temperature when liquid can exist.

9. What is the molality of a solution of 49.8 g of propanol (C3H7OH) in 152 mL water, if the density of water is 1.00 g/mL?

10. Find the mass percent of CuSO4 in a solution whose density is 1.30 g/mL and whose molarity is 1.36 M.Let’s assume, that we have 1 L of the solution.

13. Vapor pressure of water at 25.0 0C is 23.8 torr. Determine the mass of glucose (molar mass = 180 g/mol) needed to add to 50.0 g of water to change the vapor pressure to 23.0 torr.

14. Determine the mass of a nonvolatile, nonionizing compound that must be added to 3.19 kg of water to lower the freezing point to -1.3 0C. The molar mass of the compound is 50.0 g/mol and Kf for water is 1.86 0C kg/mol.

i – van’t Hoff Factor. For nonionizing compounds it equals 1

19. What is the expected boiling point of a solution prepared by dissolving 5.83 g of sodium iodide (NaI) in 59.2 g of water? For water, Tbp=100.00 0C and Kbp=0.512 0C m-1.

22. For a reaction in which A and B react to form C, the following initial rate data were obtained:

What is the rate law?

[A], mo/L [B], mol/L Rate of formation of C, mol/L sec

0.10 0.10 1.00

0.10 0.20 4.00

0.20 0.20 8.00

22. For a reaction in which A and B react to form C, the following initial rate data were obtained:

Rate = k[A]m[B]n

We need to determine m and n.

[A], mo/L [B], mol/L Rate of formation of C, mol/L sec

0.10 0.10 1.00

0.10 0.20 4.00

0.20 0.20 8.00

22. For a reaction in which A and B react to form C, the following initial rate data were obtained:

Rate = k[A]m[B]n

1) For determination of m, choose rows, where concentrations of [B] are equal

[A], mo/L [B], mol/L Rate of formation of C, mol/L sec

0.10 0.10 1.00

0.10 0.20 4.00

0.20 0.20 8.00

22. For a reaction in which A and B react to form C, the following initial rate data were obtained:

Rate = k[A]m[B]n

1) For determination of n, choose rows, where concentrations of [A] are equal

[A], mo/L [B], mol/L Rate of formation of C, mol/L sec

0.10 0.10 1.00

0.10 0.20 4.00

0.20 0.20 8.00

23. A first order reaction is 45% complete at the end of 28 min. What is the length of the half-life of this reaction?

If reaction is 45% complete, it means that 55% of the reactant left.

37. Consider the reaction for which K = 48.2 at a high temperature. If an equimolar mixture of the reactants gives the concentration of the product to be 0.50 M at equilibrium, determine the equilibrium concentration of the hydrogen.

45. If an acid, HA, is 12.2 % dissociated in a 1.0 M solution, what is the Ka for this acid?

HA H2O H3O+ A-

1.0 -------- 0 0

---------

1.0 – 0.122 = 0.878 --------- 0.122 0.122

48. Silver chromate, Ag2CrO4, has a Ksp of 8.96*10-12. Calculate the solubility in mol/L of silver chromate.

1:1 molar ratio. That’s why if we find concentration of CrO4

2-, it will be equal to solubility of Ag2CrO4.

50. 15.0 mL of 0.50 M NaOH is added to a 100 mL sample of 0.376 M NH3 (Kb for NH3 = 1.8*10-5). What is the equilibrium concentration of NH4

+ ions?

Before addition:

After addition (Total volume = 115 mL):

NH3 H2O NH4+ OH-

0.327 ------ 0 0.065

-x ------ +x +x

0.327 – x ------ X 0.065 + x

52. What major species is (are) present at point III?

If we titrate disodium ascorbate, then we start with As2- in starting solution.Before 1st equivalence point (point II on scheme):

Before 2nd equivalence point (point III on scheme):

Point I. We have As2- and HAs- in the solution.Point II. We have HAs- in the solution.Point III. We have HAs- and H2As in the solution.Point IV. We have H2As in the solution.Point V. We have H2As and a bunch of HCl in the solution.

53. What volume of 0.0100 M NaOH must be added to 1.00 L of 0.0500 M HOCl to achieve a pH of 8.00? The Ka for HOCl is 3.5*10-8.

Let’s say, that we added x L of NaOH. Then if we find x, we’ll find an answer.

Total volume: (1 + x) L

Using H – H equation:

HOCl OH- H2O OCl-

Before ------ 0

After mol 0 ------ mol

54. For which of following titrations would methyl red be the best indicator?

For this problem we need to find pH at equivalence point of all given systems.A) Strong base + Strong acid pHequiv. point = 7.B) 0.100 M aniline (weak base) + 0.100 M HCl.

Conc.(BH+) = 0.1 mol/ Vtot = 0.1 mol/ 2L = 0.05 M

B HCl BH+ Cl-

Before 0.1 mol 0.1 mol 0 spec

After 0 mol 0 mol 0.1 mol spec

BH+ H2O B H3O+

0.05 ----- 0 0

- x ----- + x + x

0.05 – x ----- x x

54. For which of following titrations would methyl red be the best indicator?

C) The same, as B), just use different Kb

D) 0.100 M HF (weak acid) + 0.100 M NaOH.

Conc. (F-) = 0.1 mol/ Vtot = 0.1 mol/ 2L = 0.05 M

HF OH- F- H2O

Before 0.1 mol 0.1 mol 0 -----

After 0 mol 0 mol 0.1 mol -----

F- H2O HF OH-