Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) Which one of the following is the weakest acid?
A) HF (Ka = 6.8 × 10-4)
1)
B) HNO2 (Ka = 4.5 × 10-4 )
C) HClO (Ka = 3.0 × 10-8 )
D) Acetic acid (Ka = 1.8 × 10-5 )
E) HCN (Ka = 4.9 × 10-10)
2) The pH of a solution that contains 0.818 M acetic acid (Ka = 1.76 × 10-5 ) and 0.172 M sodium
acetate is __________.
A) 8.37
B) 9.92
C) 5.43
3) What is the conjugate acid of NH3 ?
A) NH3
B) NH3 +
D) 4.08
E) 8.57
D) NH4 OH
E) NH4 +
2)
3)
C) NH2 +
4) A substance that is capable of acting as both an acid and as a base is __________.
A) saturated
B) amphoteric
C) autosomal
D) miscible
E) conjugated
4)
5) Consider the following equilibrium.
5)
2 SO2 (g) + O2 (g)
2 SO3 (g)
The equilibrium cannot be established when __________ is/are placed in a 1.0-L container.
A) 0.75 mol SO2 (g)
B) 0.25 mol of SO2 (g) and 0.25 mol of SO3 (g)
C) 0.25 mol SO2 (g) and 0.25 mol O2 (g)
D) 1.0 mol SO3 (g)
E) 0.50 mol O2 (g) and 0.50 mol SO3 (g)
6) Of the following solutions, which has the greatest buffering capacity?
A) 0.821 M HF and 0.217 M NaF
B) 0.821 M HF and 0.909 M NaF
C) 0.121 M HF and 0.667 M NaF
D) 0.100 M HF and 0.217 M NaF
E) They are all buffer solutions and would all have the same capacity.
1
6)
7) The addition of hydrofluoric acid and __________ to water produces a buffer solution.
A) NaF
B) HCl
C) NaNO3
D) NaCl
E) NaBr
7)
8) For the endothermic reaction
8)
CaCO3 (s)
CaO (s) + CO2 (g)
^
Le Chatelier's principle predicts that __________ will result in an increase in the number of moles of
CO2 .
A) increasing the temperature
B) decreasing the temperature
C) increasing the pressure
D) removing some of the CaCO3 (s)
E) none of the above
9) A Br nsted-Lowry acid is defined as a substance that __________.
A) acts as a proton acceptor
B) acts as a proton donor
C) increases [OH- ] when placed in H2 O
9)
D) decreases [H+ ] when placed in H2 O
E) increases Ka when placed in H2O
10) The conjugate base of HSO4 - is __________.
A) SO4 2B) H3 SO4 +
C) H2 SO4
D) HSO4+
E) OH-
11) Of the following, __________ is a weak acid.
A) HClO4
B) HF
C) HNO3
D) HBr
E) HCl
10)
11)
12) What is the pH of an aqueous solution at 25.0 °C that contains 3.98 × 10-9 M hydroxide ion?
A) 7.00
B) 5.60
C) 8.40
D) 3.98
E) 9.00
12)
13) Which one of the following will change the value of an equilibrium constant?
A) changing temperature
B) varying the initial concentrations of products
C) adding other substances that do not react with any of the species involved in the equilibrium
D) varying the initial concentrations of reactants
E) changing the volume of the reaction vessel
13)
14) The magnitude of Kw indicates that __________.
14)
A) water autoionizes very quickly
B) water autoionizes only to a very small extent
C) the autoionization of water is exothermic
D) water autoionizes very slowly
2
15) What is the concentration (in M) of hydronium ions in a solution at 25.0 °C with pH = 4.282?
A) 5.22 × 10-5
B) 4.28
C) 9.71
D) 1.66 × 104
E) 1.92 × 10-10
15)
16) Of the following, which is the strongest acid?
A) HIO2
B) HIO
C) HIO3
D) HIO4
16)
17) The equilibrium constant for the gas phase reaction
17)
E) The acid strength of all of the above is the same.
N2 (g) + 3H2 (g)
2NH3 (g)
is Keq = 4.34 × 10-3 at 300°C. At equilibrium, __________.
A) reactants predominate
B) roughly equal amounts of products and reactants are present
C) only reactants are present
D) products predominate
E) only products are present
18) Ammonia is a __________.
A) strong base
B) weak base
C) salt
D) strong acid
E) weak acid
18)
19) The acid-dissociation constant, Ka , for gallic acid is 4.57 × 10-3 . What is the base-dissociation
19)
constant, Kb, for the gallate ion?
A) 2.19 × 10-12
B) 5.43 × 10-5
C) 4.57 × 10-3
D) 2.19 × 102
E) 7.81 × 10-6
3
ESSAY. Write your answer in the space provided or on a separate sheet of paper.
20) For the equilibrium
Br2(g) + Cl2(g)
2BrCl (g)
at 400 K Kf = 7.0. If 0.25 mol of Br2 and 0.55 mol of Cl 2 are introduces in a 3 L container, what will be the
equilibrium concentration of each of the components. Draw the ice table. This problem needs the quadratic equation.
4