NAME__________________________________
CHM 2046 Practice Exam 2 (Sumner) (Chapters 19, 20)
1. (5 pts) Which of the following mixtures will result in a buffer solution?
I: 50 mL of 0.10 M NaOH added to 25 mL of 0.10 M C6H5COOH (benzoic acid)
II: 50 mL of 0.10 M HBr added to 100 mL of 0.10 M CH3NH2 (methylamine)
III: 50 mL of 0.10 M HBrO added to 50 mL of 0.10 M KBrO
(1) Only II (2) Only III (3) I and III (4) II and III (5) I, II and III
2. Consider the titration of 0.540 L of 0.21 M benzoic acid with 0.56 M NaOH. What is the pH at the
equivalence point of the titration?
(1) 8.69 (2) 5.31 (3) 11.49 (4) 8.63 (5) 9.31
3.(5 pts) Calculate the pH of a solution that is 0.050 M in HCN and 0.025 M in Ba(CN)2.
(1) 7.60 (2) 8.80 (3) 9.10 (4) 9.40 (5) 10.20
4. If 50. mL of 0.010 M HCl solution is added to 50. mL of solution which is 0.10 M in HF and 0.20 M
in KF, what will be the pH of the new solution?
(1) 2.93 (2) 3.69 (3) 3.49 (4) 3.17 (5) 3.40
5. (5 pts) Consider an indicator (KHIn = 6.3 x 10–6) that ionizes as shown below. Which of the
following statements is false? HIn + H2O ⇋ H3O+ + In–
yellow blue
(1) The ionized form of the indicator results in a blue solution.
(2) In acidic solutions containing the indicator, we would expect predominantly yellow color.
(3) Adding a base to a solution containing this indicator will cause the color to become yellow.
(4) At pH = 10.0, a solution of this indicator will be blue.
(5) At pH = 3.0, most of the indicator is in the non-ionized form.
6. (5 pts) In a 0.10 M solution, a weak base is 2.0% dissociated. What is the pH?
(1) 2.70 (2) 5.40 (3) 8.60 (4) 11.30 (5) 13.00
7. (5 pts) Find the percent ionization of a 0.40 M HF solution.
(1) 0.068% (2) 0.17% (3) 1.1% (4) 4.1% (5) 4.7%
8. (5 pts) Which of the following mixtures will result in a buffer?
(1) 10 ml of 0.10M HF; 10 ml of 0.10 M HCl (2) 10 ml of 0.10 M NaF; 10 ml of 0.10 M NaOH
(3) 10 ml of 0.10 M HCl; 10 ml of 0.10 M NaF (4) 10 ml of 0.10 M HF; 10 ml of 0.10 M NaF
9. (5 pts) If 0.50 L of a buffer containing 1.0 mol HCN and 1.0 mol NaCN is diluted to a volume of 5.0
L, the pH (1) increases by 1 (2) decreases by 1 (3) increases by 10
(4) decreases by 10 (5) remains unchanged.
10. (5 pts) One of the following buffer solutions has pOH = 5.05. Which one? Hint: Solve the general
problem rather than 5 specific problems. (1) 0.10 M NH3 and 0.10 M NH4Cl
(2) 0.10 M NH3 and 0.20 M NH4Cl (3) 0.20 M NH3 and 0.10 M NH4Cl
(4) 0.050 M NH3 and 0.20 M NH4Cl (5) 0.20 M NH3 and 0.050 M NH4Cl
11. (10 pts) A 100.0 mL sample of 0.10 M NH3 is titrated with 0.10 M HNO3. Determine the pH of the
solution after the addition of 200.0 mL of HNO3.
, (1) 1.48 (2) 2.00 (3) 6.44 (4) 12.00 (5) 12.52
12. (5 pts) Consider a titration performed using acetic acid and aqueous ammonia. Which of the
following statements is correct?
(1) The solution is buffered before and after the equivalence point.
(2) The equivalence point would be at pH > 10.
(3) An acidic salt is present at the equivalence point.
(4) Methyl orange (pH color range 3.1 – 4.4) could be a suitable indicator.
(5) There is a rapid change in pH throughout the entire titration.
13. (5 pts) Which of the following substance has the least solubility in water?
(1) Cn(CN)2, Ksp = 1.0 × 10–8 (2) Cu2O, Ksp = 1.0 × 10–14 (3) CuI, Ksp = 1.0 x 10–12
14. (10 pts) What is the molar solubility of Fe(OH)3(s) in a solution that is buffered at pH 2.50 at
25°C? The Ksp of Fe(OH)3 is 6.3x10–38.
(1) 6.9 x 10–28 mol/L (2) 2.0 x 10–26 mol/L (3) 1.3 x 10–13 mol/L (4) 2.0 x 10–3 mol/L (5) 5.0 x 102 mol/L
15. (5 pts) A change in pH will significantly affect the solubility of which, if any, of the following
compounds?
(1) MgF2 (2) AgI (3) CuCl (4) None of the solubilities will be significantly affected.
16. (5 pts) While doing the Rainbow demo (Kermit Rainbow song), what 2 indicators when mixed
would give the color orange? I. phenolphthalein: red in basic solution
II. thymolphthalein: blue in basic solution III. p-nitrophenol: yellow in basic solution
(1) I and II (2) I and III (3) II and III
17. (10 pts) A 1.00 L buffer solution is 0.250 M in HF and 0.250 M in NaF. Calculate the pH of the
solution after the addition of 100.0 mL of 1.00 M HCl.
(1) 2.78 (2) 3.09 (3) 3.46 (4) 3.82 (5) 4.11
18. A 10.0-mL sample of 0.75 M CH3CH2COOH is titrated with 0.30 M NaOH. What is the pH of the
solution after 25.0 mL of NaOH have been added to the acid? Ka = 1.3 × 10–5
(1) 9.95 (2) 7.00 (3) 9.25 (4) 9.11 (5) 9.20
19. A solution contains 0.05 M Au+, 0.05 M Cu+, and 0.05 M Ag+ ions. When solid NaCl is added to
the solution, what is the order in which the chloride salts will begin to precipitate? K sp(AgCl) = 1.8 x
10–10, Ksp(AuCl) = 2.0 x 10–13, Ksp(CuCl) = 1.9 x 10–7
(1) AuCl > AgCl > CuCl (2) AuCl > AgCl > NaCl (3) AgCl > CuCl > AuCl
(4) CuCl > AgCl > AuCl (5) NaCl > CuCl > AgCl
20. A lab technician adds 0.015 mol of KOH to 1.00 L of 0.0010 M Ca(NO3)2.
Ksp = 6.5 × 10–6 for Ca(OH)2. Which of the following statements is correct?
(1) Calcium hydroxide precipitates until the solution is saturated.
(2) The solution is unsaturated and no precipitate forms.
(3) The concentration of calcium ions is reduced by the addition of the hydroxide ions.
(4) One must know Ksp for calcium nitrate to make meaningful predictions on this system.
(5) The presence of KOH will raise the solubility of Ca(NO3)2.
CHM 2046 Practice Exam 2 (Sumner) (Chapters 19, 20)
1. (5 pts) Which of the following mixtures will result in a buffer solution?
I: 50 mL of 0.10 M NaOH added to 25 mL of 0.10 M C6H5COOH (benzoic acid)
II: 50 mL of 0.10 M HBr added to 100 mL of 0.10 M CH3NH2 (methylamine)
III: 50 mL of 0.10 M HBrO added to 50 mL of 0.10 M KBrO
(1) Only II (2) Only III (3) I and III (4) II and III (5) I, II and III
2. Consider the titration of 0.540 L of 0.21 M benzoic acid with 0.56 M NaOH. What is the pH at the
equivalence point of the titration?
(1) 8.69 (2) 5.31 (3) 11.49 (4) 8.63 (5) 9.31
3.(5 pts) Calculate the pH of a solution that is 0.050 M in HCN and 0.025 M in Ba(CN)2.
(1) 7.60 (2) 8.80 (3) 9.10 (4) 9.40 (5) 10.20
4. If 50. mL of 0.010 M HCl solution is added to 50. mL of solution which is 0.10 M in HF and 0.20 M
in KF, what will be the pH of the new solution?
(1) 2.93 (2) 3.69 (3) 3.49 (4) 3.17 (5) 3.40
5. (5 pts) Consider an indicator (KHIn = 6.3 x 10–6) that ionizes as shown below. Which of the
following statements is false? HIn + H2O ⇋ H3O+ + In–
yellow blue
(1) The ionized form of the indicator results in a blue solution.
(2) In acidic solutions containing the indicator, we would expect predominantly yellow color.
(3) Adding a base to a solution containing this indicator will cause the color to become yellow.
(4) At pH = 10.0, a solution of this indicator will be blue.
(5) At pH = 3.0, most of the indicator is in the non-ionized form.
6. (5 pts) In a 0.10 M solution, a weak base is 2.0% dissociated. What is the pH?
(1) 2.70 (2) 5.40 (3) 8.60 (4) 11.30 (5) 13.00
7. (5 pts) Find the percent ionization of a 0.40 M HF solution.
(1) 0.068% (2) 0.17% (3) 1.1% (4) 4.1% (5) 4.7%
8. (5 pts) Which of the following mixtures will result in a buffer?
(1) 10 ml of 0.10M HF; 10 ml of 0.10 M HCl (2) 10 ml of 0.10 M NaF; 10 ml of 0.10 M NaOH
(3) 10 ml of 0.10 M HCl; 10 ml of 0.10 M NaF (4) 10 ml of 0.10 M HF; 10 ml of 0.10 M NaF
9. (5 pts) If 0.50 L of a buffer containing 1.0 mol HCN and 1.0 mol NaCN is diluted to a volume of 5.0
L, the pH (1) increases by 1 (2) decreases by 1 (3) increases by 10
(4) decreases by 10 (5) remains unchanged.
10. (5 pts) One of the following buffer solutions has pOH = 5.05. Which one? Hint: Solve the general
problem rather than 5 specific problems. (1) 0.10 M NH3 and 0.10 M NH4Cl
(2) 0.10 M NH3 and 0.20 M NH4Cl (3) 0.20 M NH3 and 0.10 M NH4Cl
(4) 0.050 M NH3 and 0.20 M NH4Cl (5) 0.20 M NH3 and 0.050 M NH4Cl
11. (10 pts) A 100.0 mL sample of 0.10 M NH3 is titrated with 0.10 M HNO3. Determine the pH of the
solution after the addition of 200.0 mL of HNO3.
, (1) 1.48 (2) 2.00 (3) 6.44 (4) 12.00 (5) 12.52
12. (5 pts) Consider a titration performed using acetic acid and aqueous ammonia. Which of the
following statements is correct?
(1) The solution is buffered before and after the equivalence point.
(2) The equivalence point would be at pH > 10.
(3) An acidic salt is present at the equivalence point.
(4) Methyl orange (pH color range 3.1 – 4.4) could be a suitable indicator.
(5) There is a rapid change in pH throughout the entire titration.
13. (5 pts) Which of the following substance has the least solubility in water?
(1) Cn(CN)2, Ksp = 1.0 × 10–8 (2) Cu2O, Ksp = 1.0 × 10–14 (3) CuI, Ksp = 1.0 x 10–12
14. (10 pts) What is the molar solubility of Fe(OH)3(s) in a solution that is buffered at pH 2.50 at
25°C? The Ksp of Fe(OH)3 is 6.3x10–38.
(1) 6.9 x 10–28 mol/L (2) 2.0 x 10–26 mol/L (3) 1.3 x 10–13 mol/L (4) 2.0 x 10–3 mol/L (5) 5.0 x 102 mol/L
15. (5 pts) A change in pH will significantly affect the solubility of which, if any, of the following
compounds?
(1) MgF2 (2) AgI (3) CuCl (4) None of the solubilities will be significantly affected.
16. (5 pts) While doing the Rainbow demo (Kermit Rainbow song), what 2 indicators when mixed
would give the color orange? I. phenolphthalein: red in basic solution
II. thymolphthalein: blue in basic solution III. p-nitrophenol: yellow in basic solution
(1) I and II (2) I and III (3) II and III
17. (10 pts) A 1.00 L buffer solution is 0.250 M in HF and 0.250 M in NaF. Calculate the pH of the
solution after the addition of 100.0 mL of 1.00 M HCl.
(1) 2.78 (2) 3.09 (3) 3.46 (4) 3.82 (5) 4.11
18. A 10.0-mL sample of 0.75 M CH3CH2COOH is titrated with 0.30 M NaOH. What is the pH of the
solution after 25.0 mL of NaOH have been added to the acid? Ka = 1.3 × 10–5
(1) 9.95 (2) 7.00 (3) 9.25 (4) 9.11 (5) 9.20
19. A solution contains 0.05 M Au+, 0.05 M Cu+, and 0.05 M Ag+ ions. When solid NaCl is added to
the solution, what is the order in which the chloride salts will begin to precipitate? K sp(AgCl) = 1.8 x
10–10, Ksp(AuCl) = 2.0 x 10–13, Ksp(CuCl) = 1.9 x 10–7
(1) AuCl > AgCl > CuCl (2) AuCl > AgCl > NaCl (3) AgCl > CuCl > AuCl
(4) CuCl > AgCl > AuCl (5) NaCl > CuCl > AgCl
20. A lab technician adds 0.015 mol of KOH to 1.00 L of 0.0010 M Ca(NO3)2.
Ksp = 6.5 × 10–6 for Ca(OH)2. Which of the following statements is correct?
(1) Calcium hydroxide precipitates until the solution is saturated.
(2) The solution is unsaturated and no precipitate forms.
(3) The concentration of calcium ions is reduced by the addition of the hydroxide ions.
(4) One must know Ksp for calcium nitrate to make meaningful predictions on this system.
(5) The presence of KOH will raise the solubility of Ca(NO3)2.
