Question 1

A solution is prepared by dissolving 0.23 mol of nitrous acid and 0.27 mol of sodium nitrite in water sufficient to yield 1.00 L of solution. The addition of 0.05 mol of HCl to this buffer solution causes the pH to drop slightly. The pH does not decrease drastically because the HCl reacts with the ________ present in the buffer solution. The Ka of nitrous acid is 1.36 × 10-3.

Accepted Answer

A) H2O 
B) H3O+ 
C) nitrite ion 
D) nitrous acid 
E) This is a buffer solution: the pH does not change at all upon addition of acid or base.

Question 2

What is the pH of the resulting solution if 45 mL of 0.432 mol L-1 methylamine, CH3NH2, is added to 15 mL of 0.234 mol L-1 HCl? Assume that the volumes of the solutions are additive. Ka = 2.70 × 10-11 for CH3NH3+.

Accepted Answer

A) 2.77 
B) 4.09 
C) 9.91 
D) 11.23

Question 3

A 25.0 mL sample of 0.150 mol L-1 hydrazoic acid is titrated with a 0.150 mol L-1 NaOH solution. What is the pH after 13.3 mL of base is added? The Ka of hydrazoic acid is 1.9 × 10-5.

Accepted Answer

A) 4.45 
B) 1.34 
C) 3.03 
D) 4.78 
E) 4.66

Question 4

Determine the molar solubility of CaSO4 in a solution containing 0.100 mol L-1 Na2SO4. Ksp (CaSO4)= 2.4 × 10-5.

Accepted Answer

A) 4.9 × 10-3 mol L-1 
B) 2.4 × 10-4 mol L-1 
C) 5.8 × 10-10 mol L-1 
D) 1.2 × 10-5 mol L-1 
E) 0.10 mol L-1

Question 5

A 100.0 mL sample of 0.10 mol L-1 Ca(OH)2 is titrated with 0.10 mol L-1 HBr. Determine the pH of the solution after the addition of 400.0 mL HBr.

Accepted Answer

A) 1.00 
B) 1.40 
C) 1.22 
D) 1.30 
E) 2.11

Question 6

You wish to prepare a buffer containing CH3COOH with a pH of 4.24. If the pKa of acetic acid is 4.74, what ratio of CH3COO⁻/CH3COOH must you use?

Accepted Answer

A) 0.10 
B) 0.50 
C) 0.32 
D) 2.0 
E) 2.8

Question 7

If the pKa of HCOOH is 3.74 and the pH of an HCOOH/HCOONa buffer solution is 3.74, which of the following is TRUE?

Accepted Answer

A) [HCOOH] > [HCOONa] 
B) [HCOOH] = [HCOONa] 
C) [HCOOH] > [HCOONa]

Question 8

Identify the indicator that can be used at the lowest pH.

Accepted Answer

A) alizarin 
B) thymol blue 
C) crystal violet 
D) phenolphthalein 
E) alizarin yellow R

Question 9

A sample contains Ba3(PO4)2, CdS, AgCl, NH4Cl, and ZnS. Identify the precipitate formed after the addition of 6 mol L-1 HCl, followed by the addition of H2S and 0.2 mol L-1 HCl, and subsequently the addition of OH- to a pH of 8.

Accepted Answer

A) Ba3(PO4)2 
B) CdS 
C) AgCl 
D) NH4Cl 
E) ZnS

Question 10

Which of the following solutions is a good buffer system?

Accepted Answer

A) a solution that is 0.10 mol L-1 NaCl and 0.10 mol L-1 HCl 
B) a solution that is 0.10 mol L-1 HCN and 0.10 mol L-1 LiCN 
C) a solution that is 0.10 mol L-1 NaOH and 0.10 mol L-1 HNO3 
D) a solution that is 0.10 mol L-1 HNO3 and 0.10 mol L-1 KNO3 
E) a solution that is 0.10 mol L-1 HCN and 0.10 mol L-1 NaCl

Question 11

What is the [CH3COO-]/[CH3COOH] ratio necessary to make a buffer solution with a pH of 4.34? Ka = 1.8 × 10-5 for CH3COOH.

Accepted Answer

A) 0.39:1 
B) 0.91:1 
C) 1.09:1 
D) 2.5:1

Question 12

A 100.0 mL sample of 0.10 mol L-1 Ca(OH)2 is titrated with 0.10 mol L-1 HBr. Determine the pH of the solution after the addition of 100.0 mL HBr.

Accepted Answer

A) 2.00 
B) 12.00 
C) 1.30 
D) 12.70 
E) 7.00

Question 13

Which of the following acids (listed with pKa values)and its conjugate base could form a buffer with a pH of 8.10?

Accepted Answer

A) HC7H5O2, pKa = 4.19 
B) HF, pKa = 3.46 
C) HClO, pKa = 7.54 
D) HCN, pKa = 9.31 
E) HClO2, pKa = 1.96

Question 14

Calculate the pH of a solution formed by mixing 200.0 mL of 0.30 mol L-1 HClO with 100.0 mL of 0.20 mol L-1 KClO. The Ka for HClO is 2.9 × 10-8.

Accepted Answer

A) 5.99 
B) 8.01 
C) 7.54 
D) 7.06 
E) 6.46

Question 15

A sample contains Ba3(PO4)2, CdS, AgCl, NH4Cl, and ZnS. Identify the precipitate after the addition of 6 mol L-1 HCl; H2S and 0.2 mol L-1 HCl; OH- to a pH of 8; and (NH4)2HPO4 with NH3.

Accepted Answer

A) Ba3(PO4)2 
B) CdS 
C) AgCl 
D) NH4Cl 
E) ZnS

Question 16

A 100.0 mL sample of 0.20 mol L-1 HF is titrated with 0.10 mol L-1 KOH. Determine the pH of the solution after the addition of 400.0 mL of KOH. The Ka of HF is 3.5 × 10-4.

Accepted Answer

A) 13.08 
B) 12.60 
C) 13.85 
D) 12.30 
E) 12.78

Question 17

What is the pH of a solution prepared by mixing 100.00 mL of 0.020 mol L-1 Ca(OH)2 with 50.00 mL of 0.300 mol L-1 NaOH? Assume that the volumes are additive.

Accepted Answer

A) 13.05 
B) 13.10 
C) 13.28 
D) 13.58

Question 18

Identify the expression for the solubility product constant for PbCl2.

Accepted Answer

A)   
B)   
C) [Pb2+][Cl⁻]2 
D)   
E) [Pb2+]2[Cl⁻]

Question 19

The molar solubility of Ag2S is 1.26 × 10-16 mol L-1 in pure water. Calculate the Ksp for Ag2S.

Accepted Answer

A) 1.59 × 10-32 
B) 1.12 × 10-8 
C) 6.81 × 10-63 
D) 3.78 × 10-12 
E) 8.00 × 10-48

Question 20

Identify the compound that is base-insoluble.

Accepted Answer

A) PbCl2 
B) As2S 
C) CoS 
D) Ca3(PO4)2 
E) NaCl

Exam 16: Aqueous Ionic Equilibrium

What is the pH of the resulting solution if 45 mL of 0.432 mol L^-1 methylamine, CH₃NH₂, is added to 15 mL of 0.234 mol L^-1 HCl? Assume that the volumes of the solutions are additive. K_a = 2.70 × 10^-11for CH₃NH₃⁺.

A 25.0 mL sample of 0.150 mol L^-1 hydrazoic acid is titrated with a 0.150 mol L^-1 NaOH solution. What is the pH after 13.3 mL of base is added? The K_a of hydrazoic acid is 1.9 × 10^-5.

Determine the molar solubility of CaSO₄ in a solution containing 0.100 mol L^-1 Na₂SO₄. K_sp (CaSO₄) = 2.4 × 10^-5.

A 100.0 mL sample of 0.10 mol L^-1 Ca(OH) ₂ is titrated with 0.10 mol L^-1 HBr. Determine the pH of the solution after the addition of 400.0 mL HBr.

You wish to prepare a buffer containing CH₃COOH with a pH of 4.24. If the pK_a of acetic acid is 4.74, what ratio of CH₃COO⁻/CH₃COOH must you use?

If the pK_a of HCOOH is 3.74 and the pH of an HCOOH/HCOONabuffer solution is 3.74, which of the following is TRUE?

Identify the indicator that can be used at the lowest pH.

A sample contains Ba₃(PO₄) ₂,CdS, AgCl, NH₄Cl, and ZnS. Identify the precipitate formed after the addition of 6 mol L^-1 HCl, followed by the addition of H₂S and 0.2 mol L^-1 HCl, and subsequently the addition of OH^- to a pH of 8.

Which of the following solutions is a good buffer system?

What is the [CH₃COO^-]/[CH₃COOH] ratio necessary to make a buffer solution with a pH of 4.34? K_a = 1.8 × 10^-5for CH3COOH.

A 100.0 mL sample of 0.10 mol L^-1 Ca(OH) ₂ is titrated with 0.10 mol L^-1 HBr. Determine the pH of the solution after the addition of 100.0 mL HBr.

Which of the following acids (listed with pK_a values) and its conjugate base could form a buffer with a pH of 8.10?

Calculate the pH of a solution formed by mixing 200.0 mL of 0.30 mol L^-1 HClO with 100.0 mL of 0.20 mol L^-1 KClO. The K_a for HClO is 2.9 × 10^-8.

A sample contains Ba₃(PO₄) ₂,CdS, AgCl, NH₄Cl, and ZnS. Identify the precipitate after the addition of 6 mol L^-1 HCl; H₂S and 0.2 mol L^-1 HCl; OH^-to a pH of 8; and (NH₄) ₂HPO₄ with NH₃.

A 100.0 mL sample of 0.20 mol L^-1 HF is titrated with 0.10 mol L^-1 KOH. Determine the pH of the solution after the addition of 400.0 mL of KOH. The K_a of HF is 3.5 × 10^-4.

What is the pH of a solution prepared by mixing 100.00 mL of 0.020 mol L^-1 Ca(OH) ₂ with 50.00 mL of 0.300 mol L^-1 NaOH? Assume that the volumes are additive.

Identify the expression for the solubility product constant for PbCl₂.

The molar solubility of Ag₂S is 1.26 × 10^-16 mol L^-1 in pure water. Calculate the K_sp for Ag₂S.

Identify the compound that is base-insoluble.

Exam 16: Aqueous Ionic Equilibrium

What is the pH of the resulting solution if 45 mL of 0.432 mol L-1 methylamine, CH3NH2, is added to 15 mL of 0.234 mol L-1 HCl? Assume that the volumes of the solutions are additive. Ka = 2.70 × 10-11 for CH3NH3+.

A 25.0 mL sample of 0.150 mol L-1 hydrazoic acid is titrated with a 0.150 mol L-1 NaOH solution. What is the pH after 13.3 mL of base is added? The Ka of hydrazoic acid is 1.9 × 10-5.

Determine the molar solubility of CaSO4 in a solution containing 0.100 mol L-1 Na2SO4. Ksp (CaSO4) = 2.4 × 10-5.

A 100.0 mL sample of 0.10 mol L-1 Ca(OH) 2 is titrated with 0.10 mol L-1 HBr. Determine the pH of the solution after the addition of 400.0 mL HBr.

You wish to prepare a buffer containing CH3COOH with a pH of 4.24. If the pKa of acetic acid is 4.74, what ratio of CH3COO⁻/CH3COOH must you use?

If the pKa of HCOOH is 3.74 and the pH of an HCOOH/HCOONa buffer solution is 3.74, which of the following is TRUE?

Identify the indicator that can be used at the lowest pH.

A sample contains Ba3(PO4) 2, CdS, AgCl, NH4Cl, and ZnS. Identify the precipitate formed after the addition of 6 mol L-1 HCl, followed by the addition of H2S and 0.2 mol L-1 HCl, and subsequently the addition of OH- to a pH of 8.

Which of the following solutions is a good buffer system?

What is the [CH3COO-]/[CH3COOH] ratio necessary to make a buffer solution with a pH of 4.34? Ka = 1.8 × 10-5 for CH3COOH.

A 100.0 mL sample of 0.10 mol L-1 Ca(OH) 2 is titrated with 0.10 mol L-1 HBr. Determine the pH of the solution after the addition of 100.0 mL HBr.

Which of the following acids (listed with pKa values) and its conjugate base could form a buffer with a pH of 8.10?

Calculate the pH of a solution formed by mixing 200.0 mL of 0.30 mol L-1 HClO with 100.0 mL of 0.20 mol L-1 KClO. The Ka for HClO is 2.9 × 10-8.

A sample contains Ba3(PO4) 2, CdS, AgCl, NH4Cl, and ZnS. Identify the precipitate after the addition of 6 mol L-1 HCl; H2S and 0.2 mol L-1 HCl; OH- to a pH of 8; and (NH4) 2HPO4 with NH3.

A 100.0 mL sample of 0.20 mol L-1 HF is titrated with 0.10 mol L-1 KOH. Determine the pH of the solution after the addition of 400.0 mL of KOH. The Ka of HF is 3.5 × 10-4.

What is the pH of a solution prepared by mixing 100.00 mL of 0.020 mol L-1 Ca(OH) 2 with 50.00 mL of 0.300 mol L-1 NaOH? Assume that the volumes are additive.

Identify the expression for the solubility product constant for PbCl2.

The molar solubility of Ag2S is 1.26 × 10-16 mol L-1 in pure water. Calculate the Ksp for Ag2S.

Identify the compound that is base-insoluble.

What is the pH of the resulting solution if 45 mL of 0.432 mol L^-1 methylamine, CH₃NH₂, is added to 15 mL of 0.234 mol L^-1 HCl? Assume that the volumes of the solutions are additive. K_a = 2.70 × 10^-11for CH₃NH₃⁺.

A 25.0 mL sample of 0.150 mol L^-1 hydrazoic acid is titrated with a 0.150 mol L^-1 NaOH solution. What is the pH after 13.3 mL of base is added? The K_a of hydrazoic acid is 1.9 × 10^-5.

Determine the molar solubility of CaSO₄ in a solution containing 0.100 mol L^-1 Na₂SO₄. K_sp (CaSO₄) = 2.4 × 10^-5.

A 100.0 mL sample of 0.10 mol L^-1 Ca(OH) ₂ is titrated with 0.10 mol L^-1 HBr. Determine the pH of the solution after the addition of 400.0 mL HBr.

You wish to prepare a buffer containing CH₃COOH with a pH of 4.24. If the pK_a of acetic acid is 4.74, what ratio of CH₃COO⁻/CH₃COOH must you use?

If the pK_a of HCOOH is 3.74 and the pH of an HCOOH/HCOONabuffer solution is 3.74, which of the following is TRUE?

A sample contains Ba₃(PO₄) ₂,CdS, AgCl, NH₄Cl, and ZnS. Identify the precipitate formed after the addition of 6 mol L^-1 HCl, followed by the addition of H₂S and 0.2 mol L^-1 HCl, and subsequently the addition of OH^- to a pH of 8.

What is the [CH₃COO^-]/[CH₃COOH] ratio necessary to make a buffer solution with a pH of 4.34? K_a = 1.8 × 10^-5for CH3COOH.

A 100.0 mL sample of 0.10 mol L^-1 Ca(OH) ₂ is titrated with 0.10 mol L^-1 HBr. Determine the pH of the solution after the addition of 100.0 mL HBr.

Which of the following acids (listed with pK_a values) and its conjugate base could form a buffer with a pH of 8.10?

Calculate the pH of a solution formed by mixing 200.0 mL of 0.30 mol L^-1 HClO with 100.0 mL of 0.20 mol L^-1 KClO. The K_a for HClO is 2.9 × 10^-8.

A sample contains Ba₃(PO₄) ₂,CdS, AgCl, NH₄Cl, and ZnS. Identify the precipitate after the addition of 6 mol L^-1 HCl; H₂S and 0.2 mol L^-1 HCl; OH^-to a pH of 8; and (NH₄) ₂HPO₄ with NH₃.

A 100.0 mL sample of 0.20 mol L^-1 HF is titrated with 0.10 mol L^-1 KOH. Determine the pH of the solution after the addition of 400.0 mL of KOH. The K_a of HF is 3.5 × 10^-4.

What is the pH of a solution prepared by mixing 100.00 mL of 0.020 mol L^-1 Ca(OH) ₂ with 50.00 mL of 0.300 mol L^-1 NaOH? Assume that the volumes are additive.

Identify the expression for the solubility product constant for PbCl₂.

The molar solubility of Ag₂S is 1.26 × 10^-16 mol L^-1 in pure water. Calculate the K_sp for Ag₂S.