Part 2
?? 1. Consider a solution that is 0.10 M in a weak triprotic acid which is represented by the general formula H3A with the
following ionization constants.
For H3A: Ka1 = 1.0 x 10-3 Ka2 = 1.0 x 10-8 Ka3 = 1.0 x 10-12
What is the pH of the solution?
a) 2.02
b) 2.15
c) 2.25ans = a
d) 2.35
e) 2.54
?? 4. The pH of a 0.12 M solution of a weak base is 10.30. What is the value of pKb for this weak base?
a) 3.70
b) 6.48
c) 10.30ans = b
d) 5.44
e) 4.49
?? 5. Calculate the pH of 0.050 M Ba(CN)2 solution. Ba(CN)2 is a soluble ionic compound.
a) 2.80
b) 2.96
c) 11.04ans = d
d) 11.20
e) 12.40
?? 6. The [OH-] = 1.3 x 10-6 M for a 0.025 M solution of a weak base. Calculate the value of Kb for this weak base.
a) 5.2 x 10-5
b) 3.1 x 10-7
c) 7.7 x 10-9ans = e
d) 4.0 x 10-8
e) 6.8 x 10-11
?? 7. At 1470 K the value of Kp = 6.0 x 10-4 for the reaction
2CO(g) == C(graphite) + CO2(g)
CO(g) initially at 2.00 atm is in contact with graphite until equilibrium is reached. What is the partial pressure
of CO2 (g) at equilibrium?
a) 0.0024 atm
b) 0.00030 atm
c) 0.0012 atmans = a
d) 0.00060 atm
e) 0.00015 atm??
8. Calculate the pH for a buffer solution prepared by mixing 100. mL of 0.10 M HF and 200. mL of 0.10 M KF.
a) 2.82
b) 2.96
c) 3.32ans = d
d) 3.44
e) 3.53
?? 9. One of the following buffer solutions has pOH = 5.05. Which one? Hint: Solve the general problem rather than 5 specific problems.
a) 0.10 M NH3and 0.10 M NH4Cl
b) 0.10 M NH3 and 0.20 M NH4Cl
c) 0.20 M NH3 and 0.10 M NH4Clans = b
d) 0.050 M NH3 and 0.20 M NH4Cl
e) 0.20 M NH3 and 0.050 M NH4Cl
?? 10. How much NH4Cl must be added to 2.00 liters of 0.200 M aqueous ammonia to give a solution with pH = 8.20?
Assume no volume change due to the addition of NH4Cl.
a) 246 g
b) 166 g
c) 2.25 gans = a
d) 123 g
e) 14.6 g
?? 11. Consider the titration of a solution of a weak acid by adding a solution of a strong base. Which response includes all the following statements that are true, and no others?
I. The end-point cannot be detected using an indicator.
II. The pH at the equivalence point is 7.00.
III. The solution is buffered before the equivalence point.
IV. The solution is buffered both before and after the equivalence point.
V.Methyl orange (pH color range 3.1-4.4) would be a better indicator for this titration than would
thymol blue (pH range8.0-9.6).
a) II and IV
b) III
c) IV and V ans = b
d) I and III
e) IV and V
?? 12. What is the pH of the solution resulting from the addition of 20.0 mL of 0.0100 M NaOH solution to 30.0 mL
of 0.0100 M acetic acid, CH3COOH?
a) 4.56
b) 4.73
c) 4.88ans = e
d) 4.96
e) 5.05
?? 13. A 1.00-liter vessel contains the following equilibrium concentrations at 400oC: N2, 1.00 M; H2, 0.50 M;
and NH3, 0.50 M. How many moles of hydrogen must be removed from the vessel in order to increase the
concentration of nitrogen to 1.20 M?
N2 (g) + 3H2 (g) == 2NH3(g)
a) 0.94 mol
b) 1.5 mol
c) 0.33 molans =
d) 0.76 mol
e) 1.1 mol
14. Given the following reaction and its equilibrium constant at a certain temperature.
N2 (g) + 3H2 (g) == 2NH3(g)Kc = 3.6 x 108
calculate the numerical value or the equilibrium constant for the following reaction at the same temperature.
NH3(g) == 1/2N2 (g) + 3/2H2 (g)
a) 2.8 x 10-9
b) 1.9 x 104
c) 1.3 x 107ans = d
d) 5.3 x 10-5
e) 7.7 x 10-18
?? 15. Consider the reaction below at equilibrium at a certain temperature.
2SO2(g) + O2 (g) == 2SO3 (g) + heat
Which response contains all the stresses that would shift the equilibrium so as to produce more SO3 (to the right),
and only those stresses?
I. increase temperature at constant pressure
II. decrease the volume of the system at constant pressure
III. remove SO2ans = e
IV. add O2
V. increase the partial pressure of SO2
a) II and III
b) I, II, and IV
c) I and V
d) I and III
e) II, IV, and V