Deck 16: Acid-Base Equilibria and Solubility Equilibria

Question 1

Calculate the pH of a solution that is 0.410 M in HOCl and 0.050 M in NaOCl.[K_a(HOCl)= 3.2 * 10^-8]

A)0.39
B)3.94
C)6.58
D)7.49
E)8.40

Answer 1

6.58

Question 2

Calculate the pH of a buffer solution prepared by dissolving 0.20 mole of sodium cyanate (NaCNO)and 1.0 mole of cyanic acid (HCNO)in enough water to make 1.0 liter of solution.[K_a(HCNO)= 2.0 * 10^-4]

A)0
B)3.0
C)3.7
D)4.4
E)5.0

Answer 2

3.0

Question 3

What is the net ionic equation for the reaction that occurs when small amounts of hydrochloric acid are added to a HOCl/NaOCl buffer solution?

A)H⁺ + H₂O $\rarr$ H₃O⁺
B)H⁺ + OCl^- $\rarr$ HOCl
C)HOCl $\rarr$ H⁺ + OCl^-
D)H⁺ + HOCl $\rarr$ H₂OCl⁺
E)HCl + HOCl $\rarr$ H₂O + Cl₂

Answer 3

H⁺ + OCl^- $\rarr$ HOCl

Question 4

Assuming equal concentrations of conjugate base and acid, which one of the following mixtures is suitable for making a buffer solution with an optimum pH of 4.6-4.8?

A)CH₃COO₂Na / CH₃COOH (K_a = 1.8 * 10^-5)
B)NH₃ / NH₄Cl (K_a = 5.6 * 10^-10)
C)NaOCl / HOCl (K_a = 3.2 * 10^-8)
D)NaNO₂ / HNO₂ (K_a = 4.5 * 10^-4)
E)NaCl / HCl

Question 5

Which one of the following is a buffer solution?

A)0.40 M HCN and 0.10 KCN
B)0.20 M CH₃COOH
C)1.0 M HNO₃ and 1.0 M NaNO₃
D)0.10 M KCN
E)0.50 M HCl and 0.10 NaCl

Question 6

Which one of the following combinations cannot function as a buffer solution?

A)HCN and KCN
B)NH₃ and (NH₄)₂SO₄
C)HNO₃ and NaNO₃
D)HF and NaF
E)HNO₂ and NaNO₂

Question 7

Calculate the pH of a buffer solution that contains 0.25 M benzoic acid (C₆H₅CO₂H)and 0.15M sodium benzoate (C₆H₅COONa). [K_a = 6.5 * 10^-5 for benzoic acid]

A)3.97
B)4.83
C)4.19
D)3.40
E)4.41

Question 8

In which one of the following solutions will acetic acid have the greatest percent ionization?

A)0.1 M CH₃COOH
B)0.1 M CH₃COOH dissolved in 1.0 M HCl
C)0.1 M CH₃COOH plus 0.1 M CH₃COONa
D)0.1 M CH₃COOH plus 0.2 M CH₃COONa

Question 9

Consider a buffer solution prepared from HOCl and NaOCl. Which is the net ionic equation for the reaction that occurs when NaOH is added to this buffer?

A)OH^- + HOCl $\rarr$ H₂O + OCl^-
B)OH^- + OCl^- $\rarr$ HOCl + O^2-
C)Na⁺ + HOCl $\rarr$ NaCl + OH^-
D)H⁺ + HOCl $\rarr$ H₂ + OCl^-
E)NaOH + HOCl $\rarr$ H₂O + NaCl

Question 10

You have 500.0 mL of a buffer solution containing 0.20 M acetic acid (CH₃COOH)and 0.30 M sodium acetate (CH₃COONa). What will the pH of this solution be after the addition of 20.0 mL of 1.00 M NaOH solution? [K_a = 1.8 * 10^-5]

A)4.41
B)4.74
C)4.56
D)4.92
E)5.07

Question 11

Calculate the percent ionization of cyanic acid, K_a = 2.0 * 10^-4, in a buffer solution that is 0.50 M HCNO and 0.10 M NaCNO.

A)0.02%
B)0.10%
C)0.20%
D)2.0%
E)20%

Question 12

Calculate the pH of a buffer solution prepared by dissolving 0.20 mole of cyanic acid (HCNO)and 0.80 mole of sodium cyanate (NaCNO)in enough water to make 1.0 liter of solution. [K_a(HCNO)= 2.0 * 10^-4]

A)0.97
B)3.10
C)4.40
D)3.70
E)4.30

Question 13

Acid dissociation constants for phosphoric acid are given below. A buffer with a pH = 7.4 can best be made by using

A)H₃PO₄ and NaH₂PO₄.
B)NaH₂PO₄ and Na₂HPO₄.
C)Na₂HPO₄ and Na₃PO₄.
D)only NaH₂PO₄.
E)only Na₂HPO₄.

Question 14

In which one of the following solutions will acetic acid have the greatest percent ionization?

A)0.1 M CH₃COOH
B)0.1 M CH₃COOH dissolved in 0.1 M HCl
C)0.1 M CH₃COOH dissolved in 0.2 M HCl
D)0.1 M CH₃COOH plus 0.1 M CH₃COONa
E)0.1 M CH₃COOH plus 0.2 M CH₃COONa

Question 15

You have 500.0 mL of a buffer solution containing 0.30 M acetic acid (CH₃COOH)and 0.20 M sodium acetate (CH₃COONa). What will the pH of this solution be after the addition of 20.0 mL of 1.00 M NaOH solution? [K_a = 1.8 * 10^-5]

A)4.65
B)4.71
C)4.56
D)4.84
E)5.07

Question 16

Over what range of pH is a HOCl - NaOCl buffer effective?

A)pH 2.0 - pH 4.0
B)pH 7.5 - pH 9.5
C)pH 6.5 - pH 8.5
D)pH 6.5 - pH 9.5
E)pH 1.0 - pH 14.0

Question 17

You are asked to go into the lab and prepare an acetic acid - sodium acetate buffer solution with a pH of 4.00 ± 0.02. What molar ratio of CH₃COOH to CH₃COONa should be used?

A)0.18
B)0.84
C)1.19
D)5.50
E)0.10

Question 18

Assuming equal concentrations of conjugate base and acid, which one of the following mixtures is suitable for making a buffer solution with an optimum pH of 9.2-9.3?

A)CH₃COONa / CH₃COOH (K_a = 1.8 * 10^-5)
B)NH₃ / NH₄Cl (K_a = 5.6 * 10^-10)
C)NaOCl / HOCl (K_a = 3.2 * 10^-8)
D)NaNO₂ / HNO₂ (K_a = 4.5 * 10^-4)
E)NaCl / HCl

Question 19

A solution is prepared by mixing 500.mL of 0.10 M NaOCl and 500.mL of 0.20 M HOCl.What is the pH of this solution? [K_a(HOCl)= 3.2 * 10^-8]

A)4.10
B)7.00
C)7.19
D)7.49
E)7.80

Question 20

Which of the following is the most acidic solution?

A)0.10 M CH₃COOH and 0.10 M CH₃COONa
B)0.10 M CH₃COOH
C)0.10 M HNO₂
D)0.10 M HNO₂ and 0.10 M NaNO₂
E)0.10 M CH₃COONa

Question 21

Methyl red is a common acid-base indicator. It has a K_a equal to 6.3 * 10^-6. Its un-ionized form is red and its anionic form is yellow. What color would a methyl red solution have at pH = 7.8?

A)green
B)red
C)blue
D)yellow
E)violet

Question 22

What mass of ammonium nitrate must be added to 350.mL of a 0.150 M solution of ammonia to give a buffer having a pH of 9.00? (K_b(NH₃)= 1.8 * 10^-5)

A)7.6 g
B)2.4 g
C)5.4 g
D)11 g
E)3.3 g

Question 23

Calculate the pH of the solution resulting from the addition of 10.0 mL of 0.10 M NaOH to 50.0 mL of 0.10 M HCN (K_a = 4.9 * 10^-10)solution.

A)5.15
B)8.71
C)5.85
D)9.91
E)13.0

Question 24

The molar solubility of tin(II)iodide is 1.28 * 10^-2 mol/L. What is K_sp for this compound?

A)8.4 * 10^-6
B)1.28 * 10^-2
C)4.2 * 10^-6
D)1.6 * 10^-4
E)2.1 * 10^-6

Question 25

The molar solubility of manganese(II)carbonate is 4.2 * 10^-6 M. What is K_sp for this compound?

A)4.2 * 10^-6
B)8.4 * 10^-6
C)3.0 * 10^-16
D)1.8 * 10^-11
E)2.0 * 10^-3

Question 26

What mass of sodium fluoride must be added to 250.mL of a 0.100 M HF solution to give a buffer solution having a pH of 3.50? [K_a(HF)= 7.1 *10^-4]

A)0.49 g
B)1.5 g
C)3.4 g
D)2.3 g
E)0.75 g

Question 27

The molar solubility of magnesium carbonate is 1.8 * 10^-4 mol/L. What is K_sp for this compound?

A)1.8 * 10^-4
B)3.6 * 10^-4
C)1.3 * 10^-7
D)3.2 * 10^-8
E)2.8 * 10^-14

Question 28

The solubility product for chromium(III)fluoride is K_sp = 6.6 * 10^-11. What is the molar solubility of chromium(III)fluoride?

A)1.6 * 10^-3 M
B)1.2 * 10^-3 M
C)6.6 * 10^-11 M
D)2.2 * 10^-3 M
E)1.6 * 10^-6 M

Question 29

A titration of an acid and base to the equivalence point results in a noticeably acidic solution.It is likely this titration involves

A)a strong acid and a weak base.
B)a weak acid and a strong base.
C)a weak acid and a weak base (where K_a equals K_b).
D)a strong acid and a strong base.

Question 30

The solubility of strontium carbonate is 0.0011 g/100 mL at 20ºC. Calculate the K_sp value for this compound.

A)7.5 * 10^-5
B)1.5 * 10^-4
C)5.6 * 10^-9
D)7.5 * 10^-6
E)1.5 * 10^-3

Question 31

For PbCl₂ (K_sp = 2.4 * 10^-4), will a precipitate of PbCl₂ form when 0.10 L of 3.0 * 10^-2 M Pb(NO₃)₂ is added to 400 mL of 9.0 *10^-2 M NaCl?

A)Yes, because Q > K_sp.
B)No, because Q < K_sp.
C)No, because Q = K_sp.
D)Yes, because Q < K_sp.

Question 32

The molar solubility of lead(II)iodate in water is 4.0 * 10^-5 mol/L. Calculate K_sp for lead(II)iodate.

A)1.6 * 10^-9
B)6.4 * 10^-14
C)2.6 * 10^-13
D)4.0 * 10^-5
E)4.0 * 10^-15

Question 33

The solubility product for barium sulfate is 1.1 * 10^-10. Calculate the molar solubility of barium sulfate.

A)5.5 * 10^-11 mol/L
B)1.1 * 10^-5 mol/L
C)2.1 * 10^-5 mol/L
D)1.1 * 10^-10 mol/L
E)2.2 * 10^-10 mol/L

Question 34

For which type of titration will the pH be basic at the equivalence point?

A)Strong acid vs.strong base.
B)Strong acid vs.weak base.
C)Weak acid vs.strong base.
D)All of the above.
E)None of the above.

Question 35

The K_sp for silver(I)phosphate is 1.8 * 10^-18. Calculate the molar solubility of silver(I)phosphate.

A)1.6 * 10^-5 M
B)2.1 * 10^-5 M
C)3.7 * 10^-5 M
D)7.2 * 10^-1 M
E)1.8 * 10^-1 M

Question 36

What is the pH at the equivalence point in the titration of 100 mL of 0.10 M HCN (K_a = 4.9 * 10^-10)with 0.10 M NaOH?

A)3.0
B)6.0
C)7.0
D)11.0
E)12.0

Question 37

Calculate the pH at the equivalence point for the titration of 0.20 M HCl with 0.20 M NH₃ (K_b = 1.8 * 10^-5).

A)2.87
B)4.98
C)5.12
D)7.00
E)11.12

Question 38

The solubility of lead(II)iodide is 0.064 g/100 mL at 20ºC. What is the solubility product for lead(II)iodide?

A)1.1 * 10^-8
B)3.9 * 10^-6
C)1.1 * 10^-11
D)2.7 * 10^-12
E)1.4 * 10^-3

Question 39

The pH at the equivalence point of a titration may differ from 7.0 due to

A)the initial concentration of the standard solution.
B)the indicator used.
C)the self-ionization of H₂O.
D)the initial pH of the unknown.
E)hydrolysis of the salt formed.

Question 40

What is the pH at the equivalence point in the titration of 100 mL of 0.10 M HCl with 0.10 M NaOH?

A)1.0
B)6.0
C)7.0
D)8.0
E)13.0

Question 41

Will a precipitate of magnesium fluoride form when 300.mL of 1.1 * 10^-3 M MgCl₂ are added to 500.mL of 1.2 * 10^-3 M NaF? [K_sp (MgF₂)= 6.9 * 10^-9]

A)Yes, Q > K_sp
B)No, Q < K_sp
C)No, Q = K_sp
D)Yes, Q < K_sp

Question 42

Calculate the silver ion concentration in a saturated solution of silver(I)carbonate (K_sp = 8.1 *10^-12).

A)5.0 * 10^-5 M
B)2.5 * 10^-4 M
C)1.3 * 10^-4 M
D)2.0 * 10^-4 M
E)8.1 * 10^-4 M

Question 43

Calculate the minimum concentration of Cr³⁺ that must be added to 0.095 M NaF in order to initiate a precipitate of chromium(III)fluoride.(For CrF₃ , K_sp = 6.6 * 10^-11.)

A)0.023 M
B)0.032 M
C)7.7 * 10^-8 M
D)2.9 * 10^-9 M
E)6.9 * 10^-10 M

Question 44

Calculate the concentration of fluoride ions in a saturated barium fluoride (K_sp = 1.7 * 10^-6)solution.

A)7.6 * 10^-3 M
B)1.5 * 10^-2 M
C)3.4 * 10^-5 M
D)1.7 * 10^-6 M
E)3.4 * 10^-6 M

Question 45

Calculate the minimum concentration of Mg²⁺ that must be added to 0.10 M NaF in order to initiate a precipitate of magnesium fluoride. (For MgF₂ , K_sp = 6.9 * 10^-9.)

A)1.4 * 10⁷ M
B)6.9 * 10^-9 M
C)6.9 * 10^-8 M
D)1.7 * 10^-7 M
E)6.9 * 10^-7 M

Question 46

Will a precipitate of magnesium fluoride form when 200.mL of 1.9 * 10^-3 M MgCl₂ are added to 300.mL of 1.4 * 10^-2 M NaF? [K_sp (MgF₂)= 6.9 * 10^-9]

A)Yes, Q > K_sp
B)No, Q < K_sp
C)No, Q = K_sp
D)Yes, Q < K_sp

Question 47

To 1.00 L of a 0.100 M aqueous solution of the week base pyridine (C₅H₅N)is added 1.00 mL of 14.0 M NaOH. What fraction of the pyridine molecules in the resulting solution react with water to release hydroxide ions? [K_b(C₅H₅N)= 1.7 * 10^-9]

A)1.2 * 10^-7
B)4.1 * 10^-5
C)0.14
D)2.4 * 10^-10
E)1.3 * 10^-5

Question 48

Which response has both answers correct? Will a precipitate form when 250 mL of 0.33 M Na₂CrO₄ are added to 250 mL of 0.12 M AgNO₃? [K_sp(Ag₂CrO₄)= 1.1 *10^-12] What is the concentration of the silver ion remaining in solution?

A)Yes, [Ag⁺] = 2.9 * 10^-6 M.
B)Yes, [Ag⁺] = 0.060 M.
C)Yes, [Ag⁺] = 1.3 * 10^-4 M.
D)No, [Ag⁺] = 0.060 M.
E)No, [Ag⁺] = 0.105 M.

Question 49

The K_sp for silver(I)phosphate is 1.8 * 10^-18. Determine the silver ion concentration in a saturated solution of silver(I)phosphate.

A)1.6 * 10^-5 M
B)2.1 * 10^-5 M
C)3.7 * 10^-5 M
D)1.1 * 10^-13 M
E)4.8 * 10^-5 M

Question 50

Calculate the concentration of chloride ions in a saturated lead(II)chloride (K_sp = 2.4 * 10^-4)solution.

A)2.4 * 10^-4 M
B)4.8 * 10^-4 M
C)3.9 * 10^-2 M
D)1.2 * 10^-1 M
E)7.8 * 10^-2 M

Question 51

Which of the following would decrease the K_sp for PbI₂?

A)Lowering the pH of the solution
B)Adding a solution of Pb(NO₃)₂
C)Adding a solution of KI
D)None of the above-the K_sp of a compound is constant at constant temperature.

Question 52

Will a precipitate (ppt)form when 300.mL of 2.0 * 10^-5 M AgNO₃ are added to 200.mL of 2.5 * 10^-9 M NaI? Answer yes or no, and identify the precipitate if there is one.

A)Yes, the ppt is AgNO₃(s).
B)Yes, the ppt is NaNO₃(s).
C)Yes, the ppt is NaI(s).
D)Yes, the ppt is AgI(s).
E)No, a precipitate will not form.

Question 53

Find the concentration of Pb²⁺ ions in a solution made by adding 5.00 g of lead(II)iodide to 500.mL of 0.150 M KI. [For PbI₂, K_sp = 1.39 * 10^-8.]

A)3.04 * 10^-4 M
B)1.54 * 10^-7 M
C)6.18 * 10^-7 M
D)1.52 * 10^-4 M
E)9.27 * 10^-8 M

Question 54

Calculate the silver ion concentration in a saturated solution of silver(I)sulfate (K_sp = 1.4 * 10^-5).

A)1.5 * 10^-2 M
B)2.4 * 10^-2 M
C)3.0 * 10^-2 M
D)1.4 * 10^-5 M
E)None of the above.

Question 55

The solubility product for calcium phosphate is K_sp = 1.3 *10^-26. What is the molar solubility of calcium phosphate?

A)1.3 * 10^-26 M
B)1.5 * 10^-7 M
C)2.6 * 10^-6 M
D)4.6 * 10^-6 M
E)6.6 * 10^-6 M

Question 56

Will a precipitate form (yes or no)when 50.0 mL of 1.2 * 10^-3 M Pb(NO₃)₂ are added to 50.0 mL of 2.0 * 10^-4 M Na₂S? If so, identify the precipitate.

A)Yes, the precipitate is PbS.
B)Yes, the precipitate is NaNO₃.
C)Yes, the precipitate is Na₂S.
D)Yes, the precipitate is Pb(NO₃)₂.
E)No, a precipitate will not form.

Question 57

To 1.00 L of a 0.100 M aqueous solution of benzoic acid (C₆H₅COOH)is added 1.00 mL of 12.0 M HCl. What is the percentage ionization of the benzoic acid in the resulting solution? [K_a(C₆H₅COOH)= 6.5 * 10^-5]

A)3.3%
B)12%
C)1.3%
D)0.52%
E)0.065%

Question 58

Will a precipitate (ppt)form when 20.0 mL of 1.1 * 10^-3 M Ba(NO₃)₂ are added to 80.0 mL of 8.4 *10^-4 M Na₂CO₃?

A)Yes, the ppt is Ba(NO₃ )₂.
B)Yes, the ppt is NaNO₃.
C)Yes, the ppt is BaCO₃.
D)Yes, the ppt is Na₂CO₃.
E)No, a precipitate will not form.

Question 59

Will a precipitate (ppt)form when 300.mL of 5.0 * 10^-5 M AgNO₃ are added to 200.mL of 2.5 * 10^-7 M NaBr? Answer yes or no, and identify the precipitate if there is one.

A)Yes, the ppt is AgNO₃(s).
B)Yes, the ppt is AgBr(s).
C)Yes, the ppt is NaBr(s).
D)Yes, the ppt is NaNO₃(s).
E)No, a precipitate will not form.

Question 60

The K_sp value for lead(II)chloride is 2.4 * 10^-4. What is the molar solubility of lead(II)chloride?

A)2.4 * 10^-4 mol/L
B)6.2 * 10^-2 mol/L
C)7.7 * 10^-3 mol/L
D)3.9 * 10^-2 mol/L
E)6.0 * 10^-5 mol/L

Question 61

Describe how to make a sodium formate (HCOONa)/formic acid (HCOOH)buffer that has a pH of 4.77.

Question 62

Write a net ionic equation for the reaction that occurs when a small amount of hydrochloric acid is added to a buffer solution containing NH₄Cl and NH₃.

Question 63

A saturated sodium carbonate solution at 100°C contains 45.5 g of dissolved sodium carbonate per 100.mL of solution. The solubility product constant for sodium carbonate at this temperature is

A)79.0
B)0.316
C)0.0790
D)36.8
E)316

Question 64

Write a net ionic equation for the reaction occurring when a small amount of sodium hydroxide is added to a NaNO₂/HNO₂ buffer.

Question 65

A saturated sodium carbonate solution at 0°C contains 7.1 g of dissolved sodium carbonate per 100.mL of solution. The solubility product constant for sodium carbonate at this temperature is

A)1.2
B)0.30
C)3.0 * 10^-4
D)0.90
E)1.2 * 10^-3

Question 66

What volume of 0.0500 M sodium hydroxide should be added to 250.mL of 0.100 M HCOOH to obtain a solution with a pH of 4.50? [K_a(HCOOH)= 1.7 * 10^-4]

A)540 mL
B)420 mL
C)80.mL
D)340 mL
E)500.mL

Question 67

Calculate the percent ionization of formic acid in a solution that is 0.010 M HCOOH and 0.050 M HCOONa.(K_a = 1.7 * 10^-4)

Question 68

Calculate the percent ionization of formic acid in a solution that is 0.010 M HCOOH and 0.005 M HCOONa and compare your answer to the percent ionization you would calculate if the sodium formate were not present. Explain the difference, if any.(K_a = 1.7 * 10^-4)

Question 69

Write a net ionic equation for the reaction that occurs when a small amount of nitric acid is added to a NaNO₂/HNO₂ buffer.

Question 70

What is the optimum pH of a sodium formate/formic acid buffer? (For formic acid, K_a = 1.7 * 10^-4)

Question 71

What molar ratio of benzoate ion to benzoic acid would be required to prepare a buffer with a pH of 5.20? [K_a(C₆H₅COOH)= 6.5 * 10^-5]

Question 72

What volume of 0.200 M potassium hydroxide should be added to 300.mL of 0.150 M propanoic acid (C₂H₅COOH)to obtain a solution with a pH of 5.25? [K_a(C₂H₅COOH)= 1.34 * 10^-5]

A)32 mL
B)210 mL
C)160 mL
D)65 mL
E)13 mL

Question 73

Calculate the pH at the equivalence point for the titration of 0.25 M CH₃COOH with 0.25 M NaOH. (For CH₃COOH, K_a= 1.8 * 10^-5)

Question 74

Calculate the percent ionization of formic acid in a 0.010 M HCOOH solution.
(K_a = 1.7 *10^-4)

Question 75

Calculate the pH of a solution that is 0.15 M CH₃COOH and 0.75 M CH₃COONa.

Question 76

What is the effective pH range for a sodium acetate/acetic acid buffer? (For CH₃COOH, K_a = 1.8 * 10^-5)

Question 77

Write an equation showing the net reaction that occurs when a strong acid is added to a CO₃^2-/HCO₃^- buffer solution (for carbonic acid, K_a1 = 4.2 * 10^-7, K_a2 = 2.4 * 10^-8):

Question 78

Find the concentration of calcium ions in a solution made by adding 3.50 g of calcium fluoride to 750.mL of 0.125 M NaF. [For CaF₂, K_sp = 3.95 * 10^-11.]

A)3.16 * 10^-10 M
B)2.53 * 10^-9 M
C)4.29 * 10^-4 M
D)6.32 * 10^-10 M
E)2.15 * 10^-4 M

Question 79

Write an equation showing the net reaction that occurs when a strong base is added to a CO₃^2-/HCO₃^- buffer solution (for carbonic acid, K_a1 = 4.2 * 10^-7, K_a2 = 2.4 * 10^-8):

Question 80

Write a net ionic equation for the reaction occurring when a small amount of sodium hydroxide solution is added to a buffer solution containing NH₄Cl and NH₃.