Question 1

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? Kb = 6.5 × 10−4

Accepted Answer

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

Question 2

Which of the following has the highest buffer capacity?

Accepted Answer

A) 0.10 M H 2PO 4 −/0.10 M HPO 4 2− 
B) 0.50 M H 2PO 4 −/0.10 M HPO 4 2− 
C) 0.10 M H 2PO 4 −/0.50 M HPO 4 2− 
D) 0.50 M H 2PO 4 −/0.50 M HPO 4 2− 
E) They all have the same buffer capacity.

Question 3

The salts X(NO3)2 and Y(NO3)2 (where X+ and Y+ are metal ions) are dissolved in water to give a solution which is 0.1 M in each of them. Which of the answers gives the concentration of chloride ions will precipitate the most YCl2 without precipitating any XCl2? Given Ksp values: XCl2, 2 × 10−5 YCl2, 1 × 10−10

Accepted Answer

A) 1 M Cl − 
B) 0.1 M Cl − 
C) 0.01 M Cl − 
D) 0.001 M Cl − 
E) 0.0001 M Cl −

Question 4

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

Accepted Answer

A) Dissolving a small amount of Na 2HPO 4 
B) Dissolving a small amount of NaH 2PO 4 
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 5

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?

Accepted Answer

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

Question 6

Write the ion product expression for silver sulfide, Ag2S.

Accepted Answer

A)   
B)   
C)   
D)   
E)

Question 7

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 Ka2 for ascorbic acid?

Accepted Answer

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 8

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

Accepted Answer

A) is greater than 7.0. 
B) is equal to 7.0. 
C) is less than 7.0. 
D) is equal to the p K a of the acid. 
E) is equal to 14.0 − p K b, where p K b is that of the base.

Question 9

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, Ka = 6.8 × 10−5

Accepted Answer

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

Question 10

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, Ka = 6.8 × 10−4.

Accepted Answer

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

Question 11

For a diprotic acid H2A, the relationship Ka1 > Ka2 is always true.

Accepted Answer

A) True 
 B)False

Question 12

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?

Accepted Answer

A) Calcium hydroxide precipitates until the solution is saturated. 
B) The solution is unsaturated and no precipitate forms. 
C) The concentration of calcium ions is reduced by the addition of the hydroxide ions. 
D) One must know K sp for calcium nitrate to make meaningful predictions on this system. 
E) The presence of KOH will raise the solubility of Ca(NO 3)2.

Question 13

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?

Accepted Answer

A) It is a buffer, pH > pK a of formic acid. 
B) It is a buffer, pH 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.

Question 14

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? Kb = 1.8 × 10−5

Accepted Answer

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

Question 15

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

Accepted Answer

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

Question 16

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?

Accepted Answer

A) 0.9 M CO 3 2− and 0.1 M HCO 3 − 
B) 0.1 M CO 3 2− and 0.9 M HCO 3 − 
C) 0.5 M CO 3 2− and 0.5 M HCO 3 − 
D) 0.1 M CO 3 2− and 0.1 M HCO 3 − 
E) They all have the same buffer capacity.

Question 17

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? Ka = 1.8 × 10−5

Accepted Answer

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

Question 18

Use the following information to calculate the solubility product constant, Ksp, for CuCl. A saturated solution of CuCl in water was prepared and filtered. From the filtrate, 1.0 L was measured out into a beaker and evaporated to dryness. The solid CuCl residue recovered in the beaker was found to weigh 0.041g.

Accepted Answer

A) K sp = 1.7 × 10 y9 
B) K sp = 1.7 × 10 y7 
C) K sp = 1.7 × 10 −5 
D) K sp = 4.3 × 10 −4 
E) K sp = 2.1 × 10 −2

Question 19

A lab technician adds 0.20 mol of NaF to 1.00 L of 0.35 M cadmium nitrate, Cd(NO3)2. Which of the following statements is correct? Ksp = 6.44 × 10−3 for CdF2.

Accepted Answer

A) Cadmium fluoride precipitates until the solution is saturated. 
B) The solution is unsaturated and no precipitate forms. 
C) The solubility of cadmium fluoride is increased by the presence of additional fluoride ions. 
D) One must know K sp for cadmium nitrate to make meaningful predictions on this system. 
E) The presence of NaF will raise the solubility of Cd(NO 3)2.

Question 20

Increasing the concentrations of the components of a buffer solution will increase the buffer capacity.

Accepted Answer

A) True 
 B)False

Exam 19: Ionic Equilibria in Aqueous Systems

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

Which of the following has the highest buffer capacity?

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

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?

Write the ion product expression for silver sulfide, Ag₂S.

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?

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

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

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.

For a diprotic acid H₂A, the relationship K_a1 > K_a2 is always true.

A lab technician adds 0.015 mol of KOH to 1.00 L of 0.0010 M Ca(NO₃) ₂. K_sp = 6.5 × 10⁻⁶ for Ca(OH) ₂) . Which of the following statements is correct?

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 25.0-mL sample of 1.00 M NH₃is 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

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

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 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 lab technician adds 0.20 mol of NaF to 1.00 L of 0.35 M cadmium nitrate, Cd(NO₃) ₂. Which of the following statements is correct? K_sp = 6.44 × 10⁻³ for CdF₂.

Increasing the concentrations of the components of a buffer solution will increase the buffer capacity.

Exam 19: Ionic Equilibria in Aqueous Systems

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? Kb = 6.5 × 10−4

Which of the following has the highest buffer capacity?

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

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?

Write the ion product expression for silver sulfide, Ag2S.

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 Ka2 for ascorbic acid?

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

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, Ka = 6.8 × 10−5

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, Ka = 6.8 × 10−4.

For a diprotic acid H2A, the relationship Ka1 > Ka2 is always true.

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?

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 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? Kb = 1.8 × 10−5

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

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 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? Ka = 1.8 × 10−5

A lab technician adds 0.20 mol of NaF to 1.00 L of 0.35 M cadmium nitrate, Cd(NO3) 2. Which of the following statements is correct? Ksp = 6.44 × 10−3 for CdF2.

Increasing the concentrations of the components of a buffer solution will increase the buffer capacity.

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

Write the ion product expression for silver sulfide, Ag₂S.

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?

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

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.

For a diprotic acid H₂A, the relationship K_a1 > K_a2 is always true.

A lab technician adds 0.015 mol of KOH to 1.00 L of 0.0010 M Ca(NO₃) ₂. K_sp = 6.5 × 10⁻⁶ for Ca(OH) ₂) . Which of the following statements is correct?

A 25.0-mL sample of 1.00 M NH₃is 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 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 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 lab technician adds 0.20 mol of NaF to 1.00 L of 0.35 M cadmium nitrate, Cd(NO₃) ₂. Which of the following statements is correct? K_sp = 6.44 × 10⁻³ for CdF₂.