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AP Chemistry
Ch 16-17 test Multiple choice
1. According to the Arrhenius concept, an acid is a substance that
a. is capable of donating one or more H+.
b. causes an increase in the concentration of H+ in aqueous solutions.
c. can accept a pair of electrons to form a coordinate covalent bond.
d. reacts with the solvent to form the cation formed by autoionization of that
solvent.
e. tastes bitter.
2. A Brønsted-Lowry base is defined as a substance that
a. increases [H+] when placed in H2O.
b. decreases [H+] when placed in H2O.
c. increases [OH-] when placed in H2O.
d. acts as a proton acceptor.
e. acts as a proton donor.
3. A substance that is capable of acting as both an acid and as a base is
a. autosomal.
b. conjugated.
c. amphoteric.
d. autocratic.
e. miscible.
4. What is the conjugate acid of NH3?
a. NH3
b. NH2+
c. NH3+
d. NH4+
e. NH4OH
5. The conjugate base of HSO4- is
a. OH-.
b. H2SO4.
c. SO42-.
d. HSO4+.
e. H3SO4+.
6. Which solution below has the highest concentration of hydroxide ions?
a. pH = 3.21
b. pH = 12.59
c. pH = 7.93
d. pH = 9.82
e. pH = 7.00
7.
An aqueous solution contains 0.10 M NaOH at 25°C. The pH of the solution is
a. 0.10.
b. 1.00.
c. 13.00.
d. 7.00.
e. -1.00.
8.
Which one of the following is the weakest acid?
a. HF (Ka = 6.8 ×10-4)
b. HClO (Ka = 3.0 × 10-8)
c. HNO2 (Ka = 4.5 × 10-4)
d. HCN (Ka = 4.9 × 10-10)
e. Acetic acid (Ka = 1.8 × 10-5)
9. Which of the following would produce an acidic solution in water?
I.
II.
III.
IV.
V.
a.
b.
c.
d.
e.
Zn2+
CO2
O2
C2H3O2NH3
III, IV, V only
I, II, III only
I, II only
I only
IV and V only
10. If the following solutions were ranked by increasing pH value, which of the following would
be correct?
a.
b.
c.
d.
e.
Ba(OH)2 < HNO3 < Na2CO3 < NaCl < HNO2
HNO3 < Na2CO3 < NaCl < HNO2 < Ba(OH)2
HNO3 < NaCl < HNO2 < Na2CO3 < Ba(OH)2
HNO3 < HNO2 < NaCl < Na2CO3 < Ba(OH)2
HNO3 = HNO2 < NaCl < Na2CO3 < Ba(OH)2
11. The pH at the equivalence point of the titration of HC2H3O2 with NaOH is:
a.
b.
c.
d.
Less than 7
7.0
Greater than 7
Depends on the concentration of acid used
e. Unable to determine
12. Which pair would form a buffer solution?
a.
b.
c.
d.
KNO2 and NaNO2
KNO2 and HNO2
KCl and HCl
KNO2 and NaNO3
e. KNO3 and HNO3
13. A weak acid is titrated with a strong base. The pH as a function of the volume of base added
is indicated on the graph. What is the pKa of the weak acid?
a.
b.
c.
d.
12
8
4
2
e. 40
14. Which of the following solutions is basic?
a. KNO3
b. NaBr
c. KCl
d. CaSO4
e. LiF
15. Based on the structure of each, which would be the strongest acid?
a. HIO
b. HIO2
c. HIO3
d. HIO4
e. HI, O I don’t know this answer!
AP Chemistry Free Response
3. A solution is made that is 0.24M HC2H3O2, acetic acid, which has a Ka value of
1.8x10-5. Determine the pH of this solution.
2. Use the information below to answer part (a) (i)
Acid
Ka at 298 K
HOCl
2.9 x 10-8
HOBr
2.4 x 10-9
a.
(i) Which of the two acids is stronger, HOCl or HOBr? Justify your answer in
terms of Ka.
(ii) Draw a complete Lewis electron-dot diagram for the acid that you
identified in part (a) (i).
(iii) Hypoiodous acid has the formula HOI. Predict whether HOI is a stronger
acid or a weaker acid than the acid that you identified in part (a) (i).
Justify your prediction in terms of chemical bonding.
b. Write the equation for the reaction that occurs between hypochlorous acid and
water.
c. A 1.2M NaOCl solution is prepared by dissolving solid NaOCl in distilled
water at 298K. The hydrolysis reaction OCl-(aq) + H2O(l) ↔ HOCl(aq) + OH-(aq)
occurs.
(i) Write the equilibrium-constant expression for the hydrolysis reaction that
occurs between OCl- and H2O.
(ii) Calculate the value of the equilibrium constant at 298K for the hydrolysis
reaction.
(iii) Calculate the value of [OH-] in the 1.2 M NaOCl solution at 298 K
d. A buffer solution is prepared by dissolving some solid NaOCl in a soluliotn of
HOCl at 298K. The pH of the buffer solution is determined to be 6.48.
(i) Calculate the value of [H+] in the buffer solution.
(ii) Indicate which of HOCl or OCl- is present at the higher concentration in
the buffer solution. Support your answer with a calculation.
3.
NH3 + H2O ↔ NH4+ + OH-
In aqueous solution, ammonia reacts as represented above. In 0.0180 M NH3 at
25° C, the hydroxide ion concentration, [OH-], is 5.60 x 10-4 M. In answering the
following, assume that temperature is constant at 25°C and that volumes are additive.
a. Write the equilibrium-constant expression for the reaction represented above.
b. determine the pH of 0.0180M NH3
c. Determine the value of the base ionization constant, Kb , for NH3
d. Determine the percent ionization of NH3 in 0.0180 M NH3
e. In an experiment, a 20.0 mL sample of 0.0180 M NH3 was placed in a flsak
and titrated to the equivalence point and beyond using 0.0120 M HCl.
i. Determine the volume of 0.0120 M HCl that was added to reach the
equivalence point.
ii. Determine the pH of the solution in the flask after a total of 15.0 mL of
0.0120 M HCl was added.
iii. Determine the pH of the solution after in the flask after a total of 40.0
mL of 0.0120 M HCl was added.