EXAM 2 PRACTICE MULTIPLE CHOICE QUESTIONS – ANSWER KEY
1. For the following system at equilibrium, what will cause the partial pressure of HF to increase?
UO2(s) + 4 HF(g) UF4(g) + 2 H2O(g)
a. adding UO2(s) c. adding UF4(g)
b. decreasing the volumed. removing H2O(g)
2. Which of the following is a strong acid?
a. HF b. H3PO4 c. HCld. H2CO3
3. The following are strong bases EXCEPT
a. LiOH b. Al(OH)3c. KOH d. Ba(OH)2
4. For the following reaction, which of the following is a conjugate acid-base pair?
HC2O4-(aq) + H2O(l) H3O+(aq) + C2O42–(aq)
a. HC2O4–and H2O c. H2O and C2O42–
b. HC2O4–and H3O+d. HC2O4–and C2O42–
5. Which of the following is true of the following system?
CH3NH3+(aq) + OH-(aq) CH3NH2(aq) + H2O(l)
a. Equilibrium lies to the left, because H2O is a stronger acid than CH3NH3+
b. Equilibrium lies to the left, because OH-is a stronger base than CH3NH2
c. Equilibrium lies to the right, because CH3NH3+is a stronger acid than H2O
d. Equilibrium lies to the right, because OH-is a stronger acid than H2O
6. In the following reaction, which is a Brønsted-Lowry base?
HC2O4–(aq) + H2O(l) H3O+(aq) + C2O42–(aq)
a. HC2O4–b. H2Oc. H3O+d. None of these
7. When KNO2 is dissolved in water, which of the following is the principal acid-base equilibrium?
a) K(H2O)6+(aq) K(H2O)5OH(aq) + H+(aq)
b) HNO2(aq) H+ (aq) + NO2- (aq)
c) NO2- (aq) + H2O(l) HNO2(aq) + OH- (aq)
d) NO2- (aq) + H2O(l) HNO3(aq) + H+ (aq)
8. Consider the following reaction at equilibrium.
2 CO2 (g) 2 CO (g) + O2 (g) ∆H0= 514 kJ/mol
Le Châtelier’s principle predicts that adding O2 (g) to the reaction container will
a) increase the partial pressure of CO2 (g) at equilibrium.
b) increase the partial pressure of CO (g) at equilibrium.
c) increase the value of the equilibrium constant.
d) decrease the value of the equilibrium constant.
9. A Brønsted-Lowry base is defined as a substance that
a) acts as a proton donor.
b) increases [H+] when placed in water.
c) acts as a proton acceptor.
d) decreases [H+] when placed in water.
10. For the following reaction, which of the following is a conjugate acid-base pair?
H2PO4- (aq) + NH3 (aq) HPO42- (aq) + NH4+ (aq)
a) H2PO4-and NH3
b) HPO42-and NH4+
c) H2PO4-and HPO42-
d) None of the above
11. The equilibrium constant for the gas phase reaction
2 NH3 (g) N2 (g) + 3 H2 (g)
is Keq = 230 at 300 C. Which one of the following statements is true at equilibrium?
a) The reactant predominates.
b) The products predominate.
c) Only products are present.
d) Only the reactant is present.
12. Which of the following reactions corresponds to hydrolysis of NH4+in water solution?
a. NH4+(aq) + OH– (aq) NH3(aq) + H2O(l)
b. NH4+ (aq) + H2O(l) NH3(aq) + H3O+(aq)
c. NH4+ (aq) + H2O(l) NH52+(aq) + OH–(aq)
d. NH4+ (aq) NH2+(aq) + H2(g)
13. Which of the following is true?
a. HF is a stronger acid than HI, because F is more electronegative than I.
b. HF is a stronger acid than HI, because the HF bond is weaker than the HI bond.
c. HF is a weaker acid than HI, because I is more electronegative than F.
d. HF is a weaker acid than HI, because the HF bond is stronger than the HI bond.
14. Which one of the following would be expected to change the value of the equilibrium constant?
a) adding reactant
b) adding product
c) adding a catalyst
d) changing the temperature
e) decreasing the reaction vessel volume
15. Consider the following reaction at equilibrium in a closed container
4 NH3(g) + 3 O2(g)2 N2(g) + 6 H2O(g)∆H = –64.5 kJ/mol
i. Increasing the O2 partial pressure will ______the NH3 partial pressure.
a) increase b) decrease c) not change
ii. Increasing the temperature of the reaction vessel will ______the NH3 partial pressure.
a) increase b) decrease c) not change
iii. Decreasing the volume of the reaction vessel will ______the NH3 partial pressure.
a) increase b) decrease c) not change
16. What is the conjugate base of HCO3–?
a) OH–b) H2CO3c) CO32–d) HCO3+e) H3CO3+
17. What is the pH of an aqueous solution at 25.0oC in which [OH–] is 0.00250 M.
a) +2.60 b) –2.60 c) +11.4d) –11.4 e) –2.25
18. A Brønsted-Lowry acid is defined as a substance that ______.
a) decreases [H3O+] when dissolved in water
b) increases [OH–] when dissolved in water
c) acts as a proton donor
d) acts as a proton acceptor
e) acts as a electron pair donor
19. A substance that is capable of acting as both an acid and as a base is _____.
a) amphiproticb) conjugated
c) autosomal d) binary acid-base
e) miscible f) diprotic
20. The magnitude of Kw indicates that ______.
a) water autoionizes very slowly
b) water autoionizes very quickly
c) water autoionizes only to a very small extent
d) the autoionization of water is exothermic
e) water autoionizes completely
21. Which one of the following is the strongest acid?
a) HIO3b) HIO2 c) HIO d) IO4–e) I–
22. Which one of the following binary acids is the strongest?
a) CH4 b) NH3 c) H2O d) PH3 e) H2S