Deck 19: Ionic Equilibria in Aqueous Systems

Question 1

A solution is prepared by adding 100 mL of 0.2 M hydrochloric acid to 100 mL of 0.4 M sodium formate. Is this a buffer solution, and if so, what is its pH?

A) It is a buffer, pH > pK_a of formic acid.
B) It is a buffer, pH < pK_a of formic acid.
C) It is a buffer, pH = pK_a of formic acid.
D) It is a buffer, pH = pK_b of sodium formate.
E) Since hydrochloric acid is a strong acid, this is not a buffer.

Answer 1

It is a buffer, pH = pK_a of formic acid.

Question 2

Buffer solutions with the component concentrations shown below were prepared. Which of them should have the lowest pH?

A) [CH₃COOH] = 0.25 M, [CH₃COO¯] = 0.25 M
B) [CH₃COOH] = 0.75 M, [CH₃COO¯] = 0.75 M
C) [CH₃COOH] = 0.75 M, [CH₃COO¯] = 0.25 M
D) [CH₃COOH] = 0.25 M, [CH₃COO¯] = 0.75 M
E) [CH₃COOH] = 1.00 M, [CH₃COO¯] = 1.00 M

Answer 2

[CH₃COOH] = 0.75 M, [CH₃COO¯] = 0.25 M

Question 3

What will be the effect of adding 0.5 mL of 0.1 M NaOH to 100 mL of an acetate buffer in which [CH₃COOH] = [CH₃COO¯] = 0.5 M?

A) The pH will increase slightly.
B) The pH will increase significantly.
C) The pH will decrease slightly.
D) The pH will decrease significantly.
E) Since it is a buffer solution, the pH will not be affected.

Answer 3

The pH will increase slightly.

Question 4

A buffer is prepared by adding 0.5 mol of solid sodium hydroxide to 1.0 L of 1.0 M acetic acid (CH₃COOH). What is the pH of the buffer?

A) The pH will be pK_a - 0.30, where pK_a is that of acetic acid.
B) The pH will be greater than the pK_a for acetic acid.
C) The pH will be less than the the pK_a for acetic acid.
D) The pH will be equal to the pK_a for acetic acid.
E) More information is needed to solve the problem.

Question 5

What will be the effect of adding 0.5 mL of 0.1 M HCl to 100 mL of a phosphate buffer in which [H₂PO₄¯] = [HPO₄²¯] = 0.35 M?

A) The pH will increase slightly.
B) The pH will increase significantly.
C) The pH will decrease slightly.
D) The pH will decrease significantly.
E) Since it is a buffer solution, the pH will not be affected.

Question 6

A popular buffer solution consists of carbonate (CO₃²¯) and hydrogen carbonate (HCO₃¯) conjugate acid-base pair. Which, if any, of the following such buffers can neutralize the greatest amount of added hydrochloric acid, while remaining within its buffer range?

A) 1 L of 0.9 M CO₃²¯ and 0.1 M HCO₃¯
B) 1 L of 0.1 M CO₃²¯ and 0.9 M HCO₃¯
C) 1 L of 0.5 M CO₃²¯ and 0.5 M HCO₃¯
D) 1 L of 0.1 M CO₃²¯ and 0.1 M HCO₃¯
E) They can all neutralize the same amount of hydrochloric acid.

Question 7

Which of the following has the highest buffer capacity?

A) 0.10 M H₂PO₄¯/0.10 M HPO₄²¯
B) 0.50 M H₂PO₄¯/0.10 M HPO₄²¯
C) 0.10 M H₂PO₄¯/0.50 M HPO₄²¯
D) 0.50 M H₂PO₄¯/0.50 M HPO₄²¯
E) They all have the same buffer capacity.

Question 8

Which one of the following aqueous solutions, when mixed with an equal volume of 0.10 mol L¯¹ aqueous NH₃, will produce a buffer solution?

A) 0.10 mol L¯¹ HCl
B) 0.20 mol L¯¹ HCl
C) 0.10 mol L¯¹ CH₃COOH
D) 0.050 mol L¯¹ NaOH
E) 0.20 mol L¯¹ NH₄Cl

Question 9

Which of the following acids should be used to prepare a buffer with a pH of 4.5?

A) HOC₆H₄OCOOH, K_a = 1.0 *10¯³
B) C₆H₄(COOH)₂, K_a = 2.9 *0 10¯⁴
C) CH₃COOH, K_a = 1.8 * 10¯⁵
D) C₅H₅O₅COOH, K_a = 4.0 * 10¯⁶
E) HBrO, K_a = 2.3 * 10¯⁹

Question 10

A phosphate buffer (H₂PO₄¯/HPO₄²¯) has a pH of 8.3. Which of the following changes will cause the pH to increase?

A) dissolving a small amount of Na₂HPO₄
B) dissolving a small amount of NaH₂PO₄
C) adding a small amount of dilute hydrochloric acid
D) adding a small amount of dilute phosphoric acid
E) making the buffer more concentrated by removing some water

Question 11

A buffer is to be prepared by adding solid sodium acetate to 0.10 M CH₃COOH. Which of the following concentrations of sodium acetate will produce the most effective buffer?

A) 3.0 M CH₃COONa
B) 2.5 M CH₃COONa
C) 2.0 M CH₃COONa
D) 1.5 M CH₃COONa
E) 0.30 M CH₃COONa

Question 12

Which one of the following pairs of 0.100 mol L¯¹ solutions, when mixed, will produce a buffer solution?

A) 50. mL of aqueous CH₃COOH and 25. mL of aqueous HCl
B) 50. mL of aqueous CH₃COOH and 100. mL of aqueous NaOH
C) 50. mL of aqueous NaOH and 25. mL of aqueous HCl
D) 50. mL of aqueous CH₃COONa and 25. mL of aqueous NaOH
E) 50. mL of aqueous CH₃COOH and 25. mL of aqueous CH₃COONa

Question 13

A popular buffer solution consists of carbonate (CO₃²¯) and hydrogen carbonate (HCO₃¯) conjugate acid-base pair. Which, if any, of the following such buffers has the highest buffer capacity?

A) 0.9 M CO₃²¯ and 0.1 M HCO₃¯
B) 0.1 M CO₃²¯ and 0.9 M HCO₃¯
C) 0.5 M CO₃²¯ and 0.5 M HCO₃¯
D) 0.1 M CO₃²¯ and 0.1 M HCO₃¯
E) They all have the same buffer capacity.

Question 14

Buffer solutions with the component concentrations shown below were prepared. Which of them should have the highest pH?

A) [H₂PO₄¯] = 0.50 M, [HPO₄²¯] = 0.50 M
B) [H₂PO₄¯] = 1.0 M, [HPO₄²¯] = 1.0 M
C) [H₂PO₄¯] = 1.0 M, [HPO₄²¯] = 0.50 M
D) [H₂PO₄¯] = 0.50 M, [HPO₄²¯] = 1.0 M
E) [H₂PO₄¯] = 0.75 M, [HPO₄²¯] = 1.0 M

Question 15

An acetate buffer has a pH of 4.40. Which of the following changes will cause the pH to decrease?

A) dissolving a small amount of solid sodium acetate
B) adding a small amount of dilute hydrochloric acid
C) adding a small amount of dilute sodium hydroxide
D) dissolving a small amount of solid sodium chloride
E) diluting the buffer solution with water

Question 16

Citric acid has an acid dissociation constant of 8.4 *10¯⁴. It would be most effective for preparation of a buffer with a pH of:

A) 2
B) 3
C) 4
D) 5
E) 6

Question 17

A buffer is prepared by adding 100 mL of 0.50 M sodium hydroxide to 100 mL of 0.75 M propanoic acid. Is this a buffer solution, and if so, what is its pH?

A) It is a buffer, pH > pK_a of propanoic acid.
B) It is a buffer, pH < pK_a of propanoic acid.
C) It is a buffer, pH = pK_a of propanoic acid.
D) It is a buffer, pH = pK_b of sodium propanoate.
E) Since sodium hydroxide is a strong base, this is not a buffer.

Question 18

Equal volumes of the following pairs of solutions are mixed. Which pair will produce a buffer solution?

A) 0.10 mol L¯¹ HCl and 0.05 mol L¯¹ NaOH
B) 0.10 mol L¯¹ HCl and 0.15 mol L¯¹ NH₃
C) 0.10 mol L¯¹ HCl and 0.05 mol L¯¹ NH₃
D) 0.10 mol L¯¹ HCl and 0.20 mol L¯¹ CH₃COOH
E) 0.10 mol L¯¹ HCl and 0.20 mol L¯¹ NaCl

Question 19

Which, if any, of the following aqueous mixtures would be a buffer system?

A) CH₃COOH, NaH₂PO₄
B) H₂CO₃, HCO₃¯
C) H₂PO₄¯, HCO₃¯
D) HSO₄¯, HSO₃¯
E) None of these choices is correct.

Question 20

Which of the following aqueous mixtures would be a buffer system?

A) HCl, NaCl
B) HNO₃, NaNO₃
C) H₃PO₄, H₂PO₄¯
D) H₂SO₄, CH₃COOH
E) NH₃, NaOH

Question 21

You need to prepare a buffer solution with a pH of 4.00, using NaF and HF. What ratio of the ratio of [base]/[acid] should be used in making the buffer? For HF, K_a = 7.2 * 10¯⁴

A) [base]/[acid] = 0.14
B) [base]/[acid] = 0.42
C) [base]/[acid] = 2.36
D) [base]/[acid] = 7.20
E) None of these choices is correct.

Question 22

A solution is prepared by dissolving 20.0 g of K₂HPO₄ and 25.0 g of KH₂PO₄ in enough water to produce 1.0 L of solution. What is the pH of this buffer? For phosphoric acid (H₃PO₄), K_a2 = 6.2 *10¯⁸

A) 7.70
B) 7.42
C) 7.21
D) 7.00
E) 6.72

Question 23

What is the pH of a buffer that consists of 0.45 M CH₃COOH and 0.35 M CH₃COONa? K_a = 1.8 *10¯⁵

A) 4.49
B) 4.64
C) 4.85
D) 5.00
E) 5.52

Question 24

You need to use KH₂PO₄ and K₂HPO₄ to prepare a buffer with a pH of 7.45. Which of the following ratios of [base]/[acid] is required? For phosphoric acid, (H₃PO₄), K_a2 = 6.2 *10¯⁸

A) [base]/[acid] = 1.75
B) [base]/[acid] = 1.27
C) [base]/[acid] = 1.24
D) [base]/[acid] = 0.79
E) [base]/[acid] = 0.57

Question 25

A buffer is prepared by adding 150 mL of 1.0 M NaOH to 250 mL of 1.0 M NaH₂PO₄. How many moles of HCl must be added to this buffer solution to change the pH by 0.18 units? If necessary, assume the total volume remains unchanged at 400 mL.

A) 0.025 mol HCl
B) 0.063 mol HCl
C) 0.082 mol HCl
D) 0.50 mol HCl
E) 1.0 mol HCl

Question 26

What is the pH of a solution that consists of 0.50 M H₂C₆H₆O₆ (ascorbic acid) and 0.75 M NaHC₆H₆O₆ (sodium ascorbate)? For ascorbic acid, K_a = 6.8 *10¯⁵

A) 3.76
B) 3.99
C) 4.34
D) 4.57
E) 5.66

Question 27

An acetic acid buffer containing 0.50 M CH₃COOH and 0.50 M CH₃COONa has a pH of 4.74. What will the pH be after 0.0020 mol of HCl has been added to 100.0 mL of the buffer?

A) 4.77
B) 4.71
C) 4.68
D) 4.62
E) None of these choices is correct.

Question 28

What is the pH of a buffer that consists of 0.20 M NaH₂PO₄ and 0.40 M Na₂HPO₄? For NaH₂PO₄, K_a = 6.2*10¯⁸

A) 6.51
B) 6.91
C) 7.51
D) 7.90
E) 8.13

Question 29

A buffer is prepared by adding 300.0 mL of 2.0 M NaOH to 500.0 mL of 2.0 M CH₃COOH. What is the pH of this buffer? K_a = 1.8 * 10¯⁵

A) 4.57
B) 4.52
C) 4.87
D) 4.92
E) 4.97

Question 30

The pH of blood is 7.35. It is maintained in part by the buffer system composed of carbonic acid (H₂CO₃) and the bicarbonate (hydrogen carbonate, HCO₃¯) ion. What is the ratio of [bicarbonate]/[carbonic acid] at this pH? For carbonic acid, K_a1 = 4.2 * 10¯⁷

A) [bicarbonate]/[carbonic acid] = 0.11
B) [bicarbonate]/[carbonic acid] = 0.38
C) [bicarbonate]/[carbonic acid] = 2.65
D) [bicarbonate]/[carbonic acid] = 9.4
E) None of these choices is correct.

Question 31

What is the [H₃O⁺] in a solution that consists of 1.5 M NH₃ and 2.5 NH₄Cl? K_b = 1.8 * 10¯⁵

A) 1.1 * 10¯⁵ M
B) 3.0 * 10¯⁶ M
C) 3.3 * 10¯⁹ M
D) 9.3 * 10¯¹⁰ M
E) None of these choices is correct.

Question 32

What mass of NaF must be added to 50.0 mL of a 0.500 M HF solution to achieve a pH of 3.25? For HF, K_a = 7.2 * 10¯⁴

A) 1.3 g
B) 0.69 g
C) 6.9 g
D) 23 g
E) 1.5 g

Question 33

A buffer is prepared by adding 1.00 L of 1.0 M HCl to 750 mL of 1.5 M NaHCOO. What is the pH of this buffer? K_a = 1.7 * 10¯⁴

A) 2.87
B) 3.72
C) 3.82
D) 3.95
E) 4.66

Question 34

What is the [H₃O⁺] in a solution that consists of 1.2 M HClO and 2.3 M NaClO? K_a = 3.5 *10¯⁸

A) 7.8 * 10¯⁹ M
B) 1.8 * 10¯⁸ M
C) 6.7 * 10¯⁸ M
D) 1.6 *10¯⁷ M
E) None of these choices is correct.

Question 35

What is the [H₃O⁺] in a buffer that consists of 0.30 M HCOOH and 0.20 M HCOONa? For HCOOH, K_a = 1.7 * 10¯⁴

A) 1.1 * 10¯⁴ M
B) 2.6 *10¯⁴ M
C) 4.3* 10¯⁴ M
D) 6.7 *10¯⁵ M
E) None of these choices is correct.

Question 36

What is the [H₃O⁺] in a solution that consists of 0.15 M C₂N₂H₈ (ethylene diamine) and 0.35 C₂N₂H₉Cl? K_b = 4.7 * 10¯⁴

A) 2.0 * 10¯³ M
B) 1.1 * 10¯³ M
C) 6.3 * 10¯⁹ M
D) 2.1 * 10¯¹⁰ M
E) 5.0 * 10¯¹¹ M

Question 37

A solution is prepared by adding 500 mL of 0.3 M NaClO to 500 mL of 0.4 M HClO. What is the pH of this solution?

A) The pH will be greater than the pK_a of hypochlorous acid.
B) The pH will be less than the pK_a of hypochlorous acid.
C) The pH will be equal to the pK_a of hypochlorous acid.
D) The pH will equal the pK_b of sodium hypochlorite.
E) None of these choices is correct.

Question 38

If 10.0 g of NaF and 20.0 g of HF are dissolved in water to make one liter of solution, what will the pH be? For HF, K_a = 6.8 *10¯⁴

A) 7.13
B) 2.54
C) 1.57
D) 3.17
E) 4.86

Question 39

A formic acid buffer containing 0.50 M HCOOH and 0.50 M HCOONa has a pH of 3.77. What will the pH be after 0.010 mol of NaOH has been added to 100.0 mL of the buffer?

A) 3.67
B) 3.78
C) 3.81
D) 3.85
E) 3.95

Question 40

What is the pK_a for the acid HA if a solution of 0.65 M HA and 0.85 M NaA has a pH of 4.75?

A) < 4.00
B) 4.63
C) 4.87
D) 5.02
E) > 5.50

Question 41

The indicator propyl red has K_a = 3.3 * 10¯⁶. What would be the approximate pH range over which it would change color?

A) 3.5 to 5.5
B) 4.5 to 6.5
C) 5.5 to 7.5
D) 6.5 to 8.5
E) None of these choices is correct.

Question 42

When a weak acid is titrated with a strong base, the pH at the equivalence point

A) is greater than 7.0.
B) is equal to 7.0.
C) is less than 7.0.
D) is equal to the pK_a of the acid.
E) is equal to 14.0 - pK_b, where pK_b is that of the base.

Question 43

When a weak acid is titrated with a weak base, the pH at the equivalence point

A) is greater than 7.0.
B) is equal to 7.0.
C) is less than 7.0.
D) is determined by the sizes of K_a and K_b.
E) is no longer affected by addition of base.

Question 44

Which one of the following is the best representation of the titration curve which will be obtained in the titration of a weak base (0.10 mol L¯¹) with HCl of the same concentration?

A)
B)
C)
D)
E)

Question 45

When a strong acid is titrated with a weak base, the pH at the equivalence point

A) is greater than 7.0.
B) is equal to 7.0.
C) is less than 7.0.
D) is equal to the pK_a of the acid.
E) is equal to the pK_b of the base.

Question 46

A 25.0-mL sample of 0.35 M HCOOH is titrated with 0.20 M KOH. What is the pH of the solution after 25.0 mL of KOH has been added to the acid? K_a = 1.77 * 10¯⁴

A) 4.00
B) 3.88
C) 3.63
D) 3.51
E) 3.47

Question 47

Which of the following indicators would be the best to use when 0.050 M benzoic acid (K_a = 6.6*10¯⁵) is titrated with 0.05 M NaOH?

A) bromphenol blue, pH range: 3.0 to 4.5
B) bromcresol green, pH range: 3.8 to 5.4
C) alizarin, pH range: 5.7 to 7.2
D) phenol red, pH range: 6.9 to 8.2
E) phenolphthalein, pH range: 8.0 to 10.1

Question 48

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 22.0 mL of NaOH have been added to the acid? K_a = 1.3 * 10¯⁵

A) 5.75
B) 4.94
C) 4.83
D) 4.02
E) 3.95

Question 49

A 35.0-mL sample of 0.20 M LiOH is titrated with 0.25 M HCl. What is the pH of the solution after 23.0 mL of HCl have been added to the base?

A) 1.26
B) 1.67
C) 12.33
D) 12.74
E) 13.03

Question 50

At the equivalence point in an acid-base titration

A) the [H₃O⁺] equals the K_a of the acid.
B) the [H₃O⁺] equals the K_a of the indicator.
C) the amounts of acid and base which have been combined are in their stoichiometric ratio.
D) the pH is 7.0.
E) the pH has reached a maximum.

Question 51

A 50.0-mL sample of 0.50 M HCl is titrated with 0.50 M NaOH. What is the pH of the solution after 28.0 mL of NaOH have been added to the acid?

A) 0.85
B) 0.75
C) 0.66
D) 0.49
E) 3.8

Question 52

A 25.0-mL sample of 0.10 M C₂H₃NH₂ (ethylamine) is titrated with 0.15 M HCl. What is the pH of the solution after 9.00 mL of acid have been added to the amine? K_b = 6.5 *10¯⁴

A) 11.08
B) 10.88
C) 10.74
D) 10.55
E) 10.49

Question 53

When 20.0 mL of 0.15 M hydrochloric acid is mixed with 20.0 mL of 0.10 M sodium hydroxide, the pH of the resulting solution is

A) 0.00
B) 12.40
C) 1.60
D) 0.82
E) 7.00

Question 54

Which one of the following is the best representation of the titration curve which will be obtained in the titration of a weak acid (0.10 mol L¯¹) with a strong base of the same concentration?

A)
B)
C)
D)
E)

Question 55

A 25.0-mL sample of 1.00 M NH₃ is titrated with 0.15 M HCl. What is the pH of the solution after 15.00 mL of acid have been added to the ammonia solution? K_b = 1.8 * 10¯⁵

A) 10.26
B) 9.30
C) 9.21
D) 8.30
E) 8.21

Question 56

A 20.0-mL sample of 0.30 M HClO was titrated with 0.30 M NaOH. The following data were collected during the titration. What is the K_a for HClO?

A) 1.1 * 10¯⁷
B) 3.5 * 10¯⁸
C) 1.2 * 10¯⁸
D) 4.9 * 10¯¹¹
E) None of these choices is correct.

Question 57

When a strong acid is titrated with a strong base, the pH at the equivalence point

A) is greater than 7.0.
B) is equal to 7.0.
C) is less than 7.0, but is not 3.5.
D) is equal to the pK_a of the acid.
E) is equal to 3.5.

Question 58

A 20.0-mL sample of 0.25 M HNO₃ is titrated with 0.15 M NaOH. What is the pH of the solution after 30.0 mL of NaOH have been added to the acid?

A) 2.00
B) 1.60
C) 1.05
D) 1.00
E) None of these choices is correct.

Question 59

Which one of the following is the best representation of the titration curve which will be obtained in the titration of a weak diprotic acid H₂A (0.10 mol L¯¹) with a strong base of the same concentration?

A)
B)
C)
D)
E)

Question 60

A 20.0-mL sample of 0.30 M HBr is titrated with 0.15 M NaOH. What is the pH of the solution after 40.3 mL of NaOH have been added to the acid?

A) 2.95
B) 3.13
C) 10.87
D) 11.05
E) 13.14

Question 61

Calculate the solubility of silver oxalate, Ag₂C₂O₄, in pure water. K_sp = 1.0 * 10¯¹¹

A) 1.4 *10¯⁴ M
B) 8.2 * 10¯⁵ M
C) 5.4 * 10¯⁵ M
D) 3.2 * 10¯⁶ M
E) 2.5 * 10¯¹² M

Question 62

The solubility of lead(II) chloride is 0.45 g/100 mL of solution. What is the K_sp of PbCl₂?

A) 4.9 * 10¯²
B) 1.7 * 10¯⁵
C) 8.5 * 10¯⁶
D) 4.2 * 10¯⁶
E) < 1.0 * 10¯⁶

Question 63

Write the ion product expression for calcium phosphate, Ca₃(PO₄)₂.

A)
B)
C)
D)
E) None of these choices is correct.

Question 64

What volume of 0.500 M H₂SO₄ is needed to react completely with 20.0 mL of 0.400 M LiOH?

A) 4.00 mL
B) 8.00 mL
C) 12.5 mL
D) 16.0 mL
E) 32.0 mL

Question 65

A 20.0-mL sample of 0.50 M H₂C₆H₆O₆ (ascorbic acid, a diprotic acid) was titrated with 0.50 M NaOH. The following data were gathered during the titration. What is K_a2 for ascorbic acid?

A) 6.8 *10¯⁵
B) 6.2 * 10¯⁶
C) 6.2 * 10¯⁷
D) 6.2 * 10¯⁸
E) 2.8 * 10¯¹²

Question 66

The solubility of silver chromate is 0.0287 g/1.0 L of solution. What is the K_sp for Ag₂CrO₄?

A) 9.5 * 10¯⁵
B) 2.4 * 10¯⁵
C) 2.6 * 10¯¹²
D) 6.5 * 10¯¹³
E) < 1.0 * 10¯¹³

Question 67

A change in pH will significantly affect the solubility of which, if any, of the following compounds?

A) BaF₂
B) CuCl
C) CuBr
D) AgI
E) None of the solubilities will be significantly affected.

Question 68

Calculate the solubility of strontium fluoride, SrF₂, in pure water. K_sp = 2.6 * 10¯⁹

A) 1.4 * 10¯³ M
B) 3.4 * 10¯⁴ M
C) 8.7 * 10¯⁴ M
D) 5.l *10¯⁵ M
E) < 1.0 * 10¯⁵ M

Question 69

The solubility of calcium chromate is 1.56 *10¯³ g/100 mL of solution. What is the K_sp for CaCrO₄?

A) 2.4 * 10¯⁴
B) 1.5 *10¯⁵
C) 7.6 * 10¯⁶
D) 1.0 * 10¯⁸
E) < 1.0 * 10¯⁸

Question 70

A diprotic acid H₂A has K_a1 = 1 *10¯⁴ and K_a2 = 1 * 10¯⁸. The corresponding base A²¯ is titrated with aqueous HCl, both solutions being 0.1 mol L¯¹. Which one of the following diagrams best represents the titration curve which will be seen?

A)
B)
C)
D)
E)

Question 71

Write the ion product expression for magnesium fluoride, MgF₂.

A)
B)
C)
D)
E)

Question 72

When 0.300 g of a diprotic acid was titrated with 0.100 M LiOH, 40.0 mL of the LiOH solution was needed to reach the second equivalence point. Identify the formula of the diprotic acid.

A) H₂S
B) H₂C₂O₄
C) H₂C₄H₄O₆
D) H₂Se
E) H₂Te

Question 73

A saturated solution of calcium hydroxide, Ca(OH)₂, is in contact with excess solid Ca(OH)₂. Which of the following statements correctly describes what will happen when aqueous HCl (a strong acid) is added to this mixture, and system returns to equilibrium? (For Ca(OH)₂, K_sp = 6.5 * 10¯⁶)

A) The solubility of Ca(OH)₂ will be unchanged.
B) The OH¯ concentration will decrease and the Ca²⁺ concentration will increase.
C) The OH¯ concentration will increase and the Ca²⁺ concentration will decrease.
D) The concentrations of both Ca²⁺ and OH¯ will increase.
E) The solubility of Ca(OH)₂ will decrease.

Question 74

Write the ion product expression for silver sulfide, Ag₂S.

A)
B)
C)
D)
E)

Question 75

What volume of 0.200 M KOH must be added to 17.5 mL of 0.135 M H₃PO₄ to reach the third equivalence point?

A) 3.94 mL
B) 11.8 mL
C) 17.5 mL
D) 23.6 mL
E) 35.4 mL

Question 76

Calculate the solubility of barium carbonate, BaCO₃, in pure water. K_sp = 2.0 *10¯⁹

A) 1.3 * 10¯³ M
B) 3.2 * 10¯⁵ M
C) 2.2 * 10¯⁵ M
D) 4.5 *10¯⁵ M
E) 4.0 * 10¯¹⁸ M

Question 77

The solubility of silver chloride _______________ when dilute nitric is added to it.

A) increases
B) decreases
C) does not change
D) first increases, then decreases
E) first decreases, then increases

Question 78

The solubility of aluminum hydroxide in water ______________ when dilute nitric acid is added to it.

A) increases
B) decreases
C) does not change
D) first increases, then decreases
E) first decreases, then increases

Question 79

The solubility of magnesium phosphate is 2.27 * 10¯³ g/1.0 L of solution. What is the K_sp for Mg₃(PO₄)₂?

A) 6.5 * 10¯¹²
B) 6.0 *10¯¹⁴
C) 5.2 *10¯²⁴
D) 4.8* 10¯²⁶
E) 1.0 * 10¯²⁶

Question 80

A sample of a monoprotic acid (HA) weighing 0.384 g is dissolved in water and the solution is titrated with aqueous NaOH. If 30.0 mL of 0.100 M NaOH is required to reach the equivalence point, what is the molar mass of HA?

A) 37.0 g/mol
B) 81.0 g/mol
C) 128 g/mol
D) 20.3 g/mol
E) 211 g/mol