| Information: | |
| gas
constant: R = 0.08206 L·atm/mole·K
= 8.314 J/mole·K Avogadro's number: NA = 6.022 ´ 1023/mol van't Hoff equation: ln(K2/K1)= -(DH/R)(1/T2 -1/T1) normal freezing point of water: 0.00°C = 273.15K water ionization constant (25°C): Kw = 1.00 ´ 10-14 pressure: 1 atm = 760 mmHg = 760 torr exp(x) = ex, ln(ex) = x, log(10x) = x quadratic equation: ax2 + bx + c = 0, |
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Multiple choice: select one answer for each question:
1. Find the concentration of B in an equilibrium gas mixture that has [C] = 4.61 ´ 10-2 M:
B(g) 
2C(g)
, Kc =
5.38 ´
10-3
| a) |
8.5 ´ 10-2 M |
|
| b) | 9.2 ´ 10-1 M | |
| c) | 3.1 ´ 10-3 M | |
| d) | 4.0 ´ 10-1 M | |
| e) | 1.9 ´ 10-2 M | |
2.
The relationship between Kc and Kp for the reaction NO(g)
+ ½ O2(g)
NO2(g) at 477ºC is
| a) | Kc = 483 Kp | |
| b) |
Kc = 7.85 Kp |
|
| c) | Kc = 15.6 Kp | |
| d) | Kc = 2.07 ´ 10-3 Kp | |
| e) | Kc = Kp | |
3.
If Kc = 0.145 for A2 + 2B 2AB,
then for AB
B + ½ A2, Kc would equal
| a) | 0.381 | |
| b) | 2.63 | |
| c) | 0.145 | |
| d) | -0.145 | |
| e) | 6.90 | |
4. Predict the reaction direction when
[CS2] = [H2] = [CH4] = [H2S]
= 0.125 M:
CS2(g) + 4 H2(g)
CH4(g)
+ 2 H2S(g) ,
Kc = 28
| a) | reactants 
products |
||
| b) | no net reaction, system is in equilibrium | ||
| c) | reactants 
products |
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5. Which of these equilibria would be affected by pressure changes at constant temperature?
1. FeO(s) + CO(g) Fe(s)
+ CO2(g)
2. CaCO3(s)
CaO(s) + CO2(g)
3. 2Mg(s) + CO2(g)
2MgO(s) + C(s)
| a) | 1 only | |
| b) | 2 only | |
| c) | 3 only | |
| d) | 1 and 2 only | |
| e) | 2 and 3 only | |
6. The
reaction 5CO(g) + I2O5(g)
I2(g) + 5CO2(g) is exothermic. The yield
could be increased by
| a) | increasing the pressure | |
| b) | decreasing the pressure | |
| c) | increasing the temperature | |
| d) | decreasing the temperature | |
| e) | decreasing the volume of the reaction vessel | |
7. The symbol Kb(HCO3-) is the equilibrium constant for which reaction?
| a) | HCO3-
+ OH-
CO32-
+ H2O |
|
| b) | HCO3-
+ H2O CO32-
+ H3O+ |
|
| c) | HCO3-
+ H3O+
H2CO3
+ H2O |
|
| d) | HCO3-
+ H2O
H2CO3
+ OH-
|
|
| e) | 2HCO3-
H2CO3 + CO32- |
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8. The pH of a solution that has [H3O+] = 5.12 × 10-3 M is:
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| a) | 6.4 | |
| b) | 2.3 | |
| c) | 5.1 | |
| d) | 3.0 | |
9. The Bronsted concept of acids and bases says the conjugate base of NH3 would be
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| a) | OH - | |
| b) | NH4OH | |
| c) | NH2- | |
| d) | NH4+ | |
10. What is [OH-] in a solution that has [H3O+] = 3.16 × 10-5 M?
| a) | 3.16 × 10-8 M | |
| b) | 3.16 × 10-11 M | |
| c) | 3.16 × 10-9 M | |
| d) | 3.16 × 10-10 M | |
11. The concentration of H3O+ in 0.44 M hypobromous acid (HBrO, Ka = 2.3 ´ 10-9) is:
| a) | 2.6 ´ 10-4 M | |
| b) | 3.2 ´ 10-5 M | |
| c) | 1.4 ´ 10-6 M | |
| d) | 2.1 ´ 10-5 M | |
12. What is the concentration of cyanide ion CN- in 0.003 M HCN (Ka = 6.2 × 10-10)?
| a) | 1.4 ´ 10-6 M | |
| b) | 6.2 ´ 10-10 M | |
| c) | 8.4 ´ 10-7 M | |
| d) | 2.5 ´ 10-5 M | |
13. The pH of 0.033 M NH3 (Kb = 1.8 × 10-5) is
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| a) | 11.3 | |
| b) | 9.25 | |
| c) | 10.9 | |
| d) | 12.8 | |
14. Which solution has the lowest pH?
| a) | 0.10 M HNO2 | |
| b) | 0.10 M HNO3 | |
| c) | 0.10 M KNO2 | |
| d) | 0.10 M KNO3 | |
15. The correct order of increasing base strength (weaker < stronger) is:
| a) | BrO3- < BrO2- < BrO- | ||
| b) | BrO3- < BrO- < BrO2- | ||
| c) | BrO2- < BrO- < BrO3- | ||
| d) | BrO- < BrO2- < BrO3- | ||
16.
Fe3+ in the reaction
Fe3+ + 6 H2O
Fe(H2O)63+ is best described as a
| a) | Bronsted acid | |
| b) | Bronsted base | |
| c) | Lewis acid | |
| d) | Lewis base | |
| e) | Arrhenius acid | |
17. How does the acid equilibrium shift after some sodium acetate salt (CH3COONa ) is added to a solution of acetic acid (CH3COOH, Ka = 1.8 ´ 10-5)?
| a) | CH3COOH
+ H2O
H3O+ + CH3COO-
(pH increases) |
|
| b) | CH3COOH
+ H2O
H3O+ + CH3COO-
(pH increases) |
|
| c) | CH3COOH
+ H2O
H3O+ + CH3COO-
(pH decreases) |
|
| d) | CH3COOH
+ H2O
H3O+ + CH3COO-
(pH decreases) |
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18. Use the acid constants for HCN (Ka = 6 ´ 10-10) and HClO (Ka = 3 ´ 10-8) to calculate Kc for
ClO-(aq)
+ HCN(aq) CN-(aq)
+ HClO(aq)
| a) | 2 ´ 10-3 | |
| b) | 2 ´ 10-2 | |
| c) | 2 ´ 10-4 | |
| d) | 2 ´ 103 | |
| e) | 2 ´ 1012 | |
19. A diprotic acid H2A has values of Ka1 = 1.0 ´ 10-6 and Ka2 = 1.0 ´ 10-10. What is [A2-] in a 0.10 M solution of H2A?
| a) | 0.10 M | |
| b) | 0.20 M | |
| c) | 3.2 ´ 10-4 | |
| d) | 3.2 ´ 10-6 | |
| e) | 1.0 ´ 10-10 | |
20. Calculate the degree of ionization in 0.72 M acid HA (Ka = 0.12). HINT: use the quadratic equation.
| a) | 33% | |
| b) | 50% | |
| c) | 75% | |
| d) | 25% | |
| e) | 67% | |
| KEY: |  |