MULTIPLE CHOICE. (1 pt. each) Choose the one alternative that best completes the statement or answers the question.
1) What will the pH be if 0.10 moles of sodium formate (NaHCOO) is added to 1.0 L of a solution of
0.10 M formic acid (HCOOH)? (Ka for formic acid = 1.8 x 10-4)
1)
A) 3.74
B) 4.24
C) 4.74
D) 5.34
E) 8.33
2) The dilution of a buffer solution with a small amount of water will:
2)
A) lower the pH.
B) raise the pH.
C) not change the pH significantly.
D) change the [A-]/[HA] ratio
3) What is the most effective pH buffering range for a benzoic acid/benzoate buffer?
(benzoic acid Ka = 6.3 × 10-5)
3)
A) 8.8 - 10.8
B) 5.3 - 7.3
C) 4.7 - 6.7
D) 3.2 - 5.2
E) none of the above
4) How many grams of (NH4 )2 SO4 (132.14 g/mol) should be added to 425 mL of a 0.258 M solution of
4)
NH3 to acheive a buffer solution with a pH of 9.44? (Kb for NH3 = 1.8 x 10-5)
A) 4.8 g
B) 1.6 x 10-4 g
C) 0.029 g
D) 18 g
E) 114 g
5) A 20.00 mL sample of H3 PO4 is titrated to a phenolphthalein end point with 18.67 mL of 0.1885 M
NaOH. If the phenolphthalein color change occurs at the second eqivalence point, what is the
molarity of the acid.
A) 3.520 M
B) 1.088 M
C) 0.3520 M
D) 0.1760 M
E) 0.08798 M
6) A 0.542 g sample of an unknown monoprotic weak acid requires 28.67 mL of 0.1093 M NaOH for
neutralization. What is the molar mass of the acid?
A) 88.0 g/mol
B) 109 g/mol
C) 173 g/mol
D) 218 g/mol
E) 352 g/mol
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5)
6)
7) The following titration curve is for 25.00 mL of 0.100 M H3 PO4 , titrated with 0.100 M NaOH.
7)
What volume of NaOH solution was added to get to point C?
A) 20.00 mL
B) 28.20 mL
C) 37.50 mL
D) 41.93 mL
E) not enough information given
8) Using the figure in the previous question, what is the pH at point B?
8)
A) pH = pKa1
B) pH = pKa2
C) pH = pKa2 - pKa1
D) pH =
E) pH =
pKa1 + pKa2
2
pKa2 - pKa1
2
9) 25 mL of 0.10 M acetic acid is titrated with 0.10 M NaOH. What is the pH after 15 ml of NaOH have
been added? (Ka for acetic acid = 1.8 × 10-5 )
9)
A) 3.79
B) 4.92
C) 6.34
D) 11.61
E) 12.20
10) 25 mL of 0.10 M acetic acid is titrated with 0.10 M NaOH. What is the pH after 35 ml of NaOH have
been added? (Ka for acetic acid = 1.8 × 10-5 )
A) 1.61
B) 4.90
C) 7.00
D) 12.22
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E) 12.80
10)
11) What is the pH at the equivalence point of a titration of 0.20 M formic acid with 0.20 M NaOH?
(Ka for formic acid = 1.8 x 10-4)
11)
A) 4.29
B) 5.65
C) 7.00
D) 7.29
E) 8.37
12) Which of the following salts are only slightly soluble in water?
NiCO3
Zn(OH)2
K3 PO4
CuSO4
12)
CaBr2
Ca3 (PO4 )2
A) only NiCO3
B) only NiCO3 and Zn(OH)2
C) only Zn(OH)2 and Ca3(PO4 )2
D) only NiCO3 , Zn(OH)2 , and Ca3(PO4)2
E) all of the salts listed are only slightly soluble
13) In which of the following will BaSO4 be the most soluble?
13)
A) pure water
B) 0.1 M H2 SO4
C) 0.1 M BaCl2
D) 0.1 M NaHSO4
E) 0.1 M Na2SO4
14) In which of the following will CaCO3 be the most soluble?
14)
A) pure water
B) 0.1 M Na2CO3
C) 0.1 M NaCl
D) 0.1 M KOH
E) 0.1 M HNO3
15) Which of the following will be more soluble in an acidic solution than in water?
15)
A) PbI2
B) AgCl
C) BaSO4
D) CaCO3
E) Hg2 Cl2
16) Which of the following metal hydroxides is NOT amphoteric?
A) Fe(OH)3
B) Al(OH)3
C) NaOH
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16)
D) Zn(OH)2
E) Ni(OH)2
17) What is the ionic strength of a 0.125 m solution of Na2 SO4 ?
17)
A) 0.375 m
B) 0.500 m
C) 0.150 m
D) 0.125 m
E) 0.750 m
18) Which of the following has the largest molar solubility?
A) BaSO4
B) AgCl
C) Cr(OH)2
D) Fe(OH)3
18)
Ksp = 1.1 × 10-10
Ksp = 1.6 × 10-10
Ksp = 6.3 × 10-11
Ksp = 4 × 10-38
19) The solubility of Mg3(AsO4 )2 (350.8 g/mol) is 0.0158 g/L. What is its Ksp?
19)
A) 4.5 x 10-5
B) 2.4 x 10-14
C) 2.0 x 10-20
D) 6.8 x 10-47
E) VERY large because when I entered it into my calculator, it exploded
20) What is the solubility of AgCl in 3.0 M NH3?
AgCl
Ag(NH3 )2 +
20)
Ksp = 1.8 x 10 -10
Kf = 1.6 x 10 7
A) 5.6 x 10-10 M
B) 0.054 M
C) 0.16 M
D) 0.88 M
E) infinitely soluble
21) A solution that is 1 x 10-6 M Fe2+ , Cu2+, and Cd2+ , is made 0.10 M H2S and buffered at pH 1.0.
What precipitates (if any) will form?
Ksp
FeS
CuS
CdS
2 × 10-25
6 × 10-37
8 × 10-28
A) only FeS will precipitate
B) only CuS and CdS will precipitate
C) none will precipitate
D) all will precipitate
E) Justin Beiber will precipitate
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21)
TRUE/FALSE. (1 pt. each) Choose "A" if the statement is true and '"B" if the statement is false.
22) A buffer solution with a particular pH can be perpared by adding a strong acid to a weak acid
solution.
22)
23) If a solution of HCl is titrated with a solution of Ba(OH)2, the pH will be 7 at the equivalence point.
23)
24) If Qsp > Ksp, the solution is supersaturated and precipitate should form.
24)
25) In a saturated solution, Qsp = Ksp.
25)
26) Ksp values are generally not affected by changes in in temperature.
26)
27) A solution is 0.10 M Pb2+ and 0.10 M Co2+ . These ions can be completely separated using CO32-
27)
as a precipitating agent. (PbCO3 Ksp = 7.4 x 10-14, CoCO3 Ksp = 1.4 x 10 -13)
28) An inert coordination complex exchanges ligands slowly.
28)
FREE RESPONSE. Write your answer in the space provided.
29) (2 points) Will a precipitate form if 100.00 mL of 0.010M NaOH is combined with 100.00 mL of 0.010 M
Sr(NO3 )2? The Ksp of strontium hydroxide is 3.2 x 10-4.
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30) (2 points) What volumes of the following two solutions should be mixed to prepare 250.00 mL of buffer
solution with a pH of 4.24?
solution 1: acetic acid = 0.100 M
solution 2: sodium acetate = 0.100 M
31) (2 points) What will the pH be if 0.910 g of NaOH (40.00 g/mol) is added to 500.00 mL of a 0.500 M acetic
acid/acetate buffer with an initial pH of 4.59? The Ka for acetic acid is 1.8 x 10-5 .
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32) (4 points) 15.0 mL of a 0.100 M solution of malonic acid is titrated with 0.109 M NaOH. Malonic acid is shown
below:
Ka1 = 1.5 x 10 -3
Ka2 = 2.0 x 10 -6
a) What is the pH when 5.00 mL of base has been added?
b) What volume is required to get to the first midpoint (midpoint of the buffer region)?
c) What is the pH at the first and second midpoints?
d) What is the pH at the first equivalence point?
d) (1 point extra credit) What is the pH at the second equivalence point?
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33) (2 points) Using the following Ksp values:
Ksp
BaSO4
1.1 × 10-11
PbSO4
1.6 × 10-8
What are the concentrations of SO4 2-, Ba2+ , and Pb2+, in a saturated solution of BaSO4 and PbSO4 ?
[SO42-] _________________
[Ba2+] _________________
[Pb2+] _________________
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