Question 1

If the pKa of HCOOH is 3.74 and the pH of an HCOOH/HCOONa buffer solution is 3.89, which of the following is TRUE?

Accepted Answer

A) [HCOOH] [HCOONa] D) [HCOOH] >> [HCOONa] E) [HCOOH] <<< [HCOONa] A) [HCOOH] [HCOONa] D) [HCOOH] >> [HCOONa] E) [HCOOH] <<< [HCOONa]

Question 2

Calculate the pH of a solution formed by mixing 150.0 mL of 0.10 mol L-1 C6H5COOH with 100.0 mL of 0.30 mol L-1 C6H5COONa. The Ka for C6H5COOH is 6.5 × 10-5.

Accepted Answer

A) 4.19 
B) 9.69 
C) 4.49 
D) 4.31 
E) 10.51 
A) 4.19 
B) 9.69 
C) 4.49 
D) 4.31 
E) 10.51

Question 3

Determine the molar solubility of BaF2 in a solution containing 0.0750 mol L-1 LiF. Ksp (BaF2)= 1.7 × 10-6.

Accepted Answer

A) 2.3 × 10-5 mol L-1 
B) 8.5 × 10-7 mol L-1 
C) 1.2 × 10-2 mol L-1 
D) 0.075 mol L-1 
E) 3.0 × 10-4 mol L-1 
A) 2.3 × 10-5 mol L-1 
B) 8.5 × 10-7 mol L-1 
C) 1.2 × 10-2 mol L-1 
D) 0.075 mol L-1 
E) 3.0 × 10-4 mol L-1

Question 4

What is the molar solubility of AgCl in 0.10 mol L-1 NaCN if the colourless complex ion Ag(CN)2- forms? Ksp for AgCl is 1.8 × 10-10 and Kf for Ag(CN)2- is 1.0 × 1021.

Accepted Answer

A) 0.050 mol L-1 
B) 0.10 mol L-1 
C) 0.20 mol L-1 
D) 0.40 mol L-1 
A) 0.050 mol L-1 
B) 0.10 mol L-1 
C) 0.20 mol L-1 
D) 0.40 mol L-1

Question 5

Calculate the pH of a buffer that is 0.158 mol L-1 HClO and 0.099 mol L-1 NaClO. The Ka for HClO is 2.9 × 10-8.

Accepted Answer

A) 7.54 
B) 6.67 
C) 3.77 
D) 6.46 
E) 7.33 
A) 7.54 
B) 6.67 
C) 3.77 
D) 6.46 
E) 7.33

Question 6

A 25.0 mL sample of 0.150 mol L-1 hypochlorous acid is titrated with a 0.150 mol L-1 NaOH solution. What is the pH after 26.0 mL of base is added? The Ka of hypochlorous acid is 3.0 × 10-8.

Accepted Answer

A) 2.54 
B) 11.47 
C) 7.00 
D) 7.51 
E) 7.54 
A) 2.54 
B) 11.47 
C) 7.00 
D) 7.51 
E) 7.54

Question 7

Calculate the percent ionization of nitrous acid in a solution that is 0.210 mol L-1 in nitrous acid (HNO2)and 0.290 mol L-1 in potassium nitrite (KNO2). The acid dissociation constant of nitrous acid is 4.50 × 10-4.

Accepted Answer

A) 58.0 
B) 0.154 
C) 16.6 
D) 2.74 × 10-3 
E) 1.55 
A) 58.0 
B) 0.154 
C) 16.6 
D) 2.74 × 10-3 
E) 1.55

Question 8

Which of the following solutions represents a good buffer system?

Accepted Answer

A) a solution that is 0.10 mol L-1 CH3COOH and 0.10 mol L-1 CH3COOLi 
B) a solution that is 0.10 mol L-1 HF and 0.10 mol L-1 CH3COONa 
C) a solution that is 0.10 mol L-1 HCl and 0.10 mol L-1 NH4+ 
D) a solution that is 0.10 mol L-1 NaOH and 0.10 mol L-1 KOH 
E) a solution that is 0.10 mol L-1 HCl and 0.10 mol L-1 KCl 
A) a solution that is 0.10 mol L-1 CH3COOH and 0.10 mol L-1 CH3COOLi 
B) a solution that is 0.10 mol L-1 HF and 0.10 mol L-1 CH3COONa 
C) a solution that is 0.10 mol L-1 HCl and 0.10 mol L-1 NH4+ 
D) a solution that is 0.10 mol L-1 NaOH and 0.10 mol L-1 KOH 
E) a solution that is 0.10 mol L-1 HCl and 0.10 mol L-1 KCl

Question 9

Sketch the titration curve for a diprotic acid. Make sure to label the equivalence point(s)and the relative amounts of base that were added to reach them.

Accepted Answer

See Figure

Question 10

A sample contains Ba3(PO4)2, CdS, AgCl, NH4Cl, and ZnS. Identify the soluble salt remaining in the solution after the addition of 6 mol L-1 HCl, followed by the addition of H2S and 0.2 mol L-1 HCl, then the addition of OH- to a pH of 8, and finally the addition of (NH4)2HPO4 with NH3.

Accepted Answer

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

Question 11

What is the molar solubility of Mg(OH)2 in a basic solution with a pH of 12.50? Ksp for Mg(OH)2 is 5.6 × 10-12.

Accepted Answer

A) 1.8 × 10-10 mol L-1 
B) 5.6 × 10-9 mol L-1 
C) 2.4 × 10-6 mol L-1 
D) 1.1 × 10-4 mol L-1 
A) 1.8 × 10-10 mol L-1 
B) 5.6 × 10-9 mol L-1 
C) 2.4 × 10-6 mol L-1 
D) 1.1 × 10-4 mol L-1

Question 12

A buffer solution is 0.100 mol L-1 in both C6H5COOH and C6H5COOLi and has a pH of 4.19. Which of the following pH values would you expect after the addition of a small amount of a strong base?

Accepted Answer

A) 3.89 
B) 3.69 
C) 5.69 
D) 4.49 
E) 8.89 
A) 3.89 
B) 3.69 
C) 5.69 
D) 4.49 
E) 8.89

Question 13

Calculate the pH of a solution that is 0.210 mol L-1 in nitrous acid (HNO2)and 0.290 mol L-1 in potassium nitrite (KNO2). The acid dissociation constant of nitrous acid is 4.50 × 10-4.

Accepted Answer

A) 3.487 
B) 3.210 
C) 13.86 
D) 10.51 
E) 4.562 
A) 3.487 
B) 3.210 
C) 13.86 
D) 10.51 
E) 4.562

Question 14

A solution contains 0.021 mol L-1 Cl⁻ and 0.017 mol L-1 I⁻. A solution containing copper(I)ions is added to selectively precipitate one of the ions. At what concentration of copper(I)ion will a precipitate begin to form? What is the identity of the precipitate? Ksp(CuCl)= 1.0 × 10-6, Ksp(CuI)= 5.1 × 10-12.

Accepted Answer

A) 3.0 × 10-10 mol L-1, CuI 
B) 3.0 × 10-10 mol L-1, CuCl 
C) 4.8 × 10-5 mol L-1, CuCl 
D) 4.8 × 10-5 mol L-1, CuI 
E) 3.0 × 10-5 mol L-1, both CuCl and CuI are in the precipitate 
A) 3.0 × 10-10 mol L-1, CuI 
B) 3.0 × 10-10 mol L-1, CuCl 
C) 4.8 × 10-5 mol L-1, CuCl 
D) 4.8 × 10-5 mol L-1, CuI 
E) 3.0 × 10-5 mol L-1, both CuCl and CuI are in the precipitate

Question 15

A solution containing CaCl2 is mixed with a solution of Li2C2O4 to form a solution that is 2.1 × 10-5 mol L-1 in calcium ion and 4.75 × 10-5 mol L-1 in oxalate ion. What will happen once these solutions are mixed? Ksp (CaC2O4)= 2.3 × 10-9.

Accepted Answer

A) A precipitate will form since Q > Ksp for calcium oxalate. 
B) Nothing will happen since both calcium chloride and lithium oxalate are soluble compounds. 
C) Nothing will happen since calcium oxalate is extremely soluble. 
D) Nothing will happen since Ksp > Q for all possible precipitants. 
E) There is not enough information to determine the answer. 
A) A precipitate will form since Q > Ksp for calcium oxalate. 
B) Nothing will happen since both calcium chloride and lithium oxalate are soluble compounds. 
C) Nothing will happen since calcium oxalate is extremely soluble. 
D) Nothing will happen since Ksp > Q for all possible precipitants. 
E) There is not enough information to determine the answer.

Question 16

Calculate the pH of a solution formed by mixing 100.0 mL of 0.20 mol L-1 HClO with 200.0 mL of 0.30 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 
A) 5.99 
B) 8.01 
C) 7.54 
D) 7.06 
E) 6.46

Question 17

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 before the addition of any HBr.

Accepted Answer

A) 12.86 
B) 13.00 
C) 13.30 
D) 0.70 
E) 1.00 
A) 12.86 
B) 13.00 
C) 13.30 
D) 0.70 
E) 1.00

Question 18

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

Accepted Answer

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

Question 19

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 200.0 mL of KOH. The Ka of HF is 3.5 × 10-4.

Accepted Answer

A) 9.62 
B) 7.00 
C) 3.46 
D) 10.54 
E) 8.14 
A) 9.62 
B) 7.00 
C) 3.46 
D) 10.54 
E) 8.14

Question 20

What is the pH of a solution made by mixing 40.00 mL of 0.100 mol L-1 HCl with 25.00 mL of 0.100 mol L-1 KOH? Assume that the volumes of the solutions are additive.

Accepted Answer

A) 0.64 
B) 1.64 
C) 12.36 
D) 13.36 
E) 10.00 
A) 0.64 
B) 1.64 
C) 12.36 
D) 13.36 
E) 10.00

Exam 16: Aqueous Ionic Equilibrium

If the pKa of HCOOH is 3.74 and the pH of an HCOOH/HCOONa buffer solution is 3.89, which of the following is TRUE?

Calculate the pH of a solution formed by mixing 150.0 mL of 0.10 mol L-1 C6H5COOH with 100.0 mL of 0.30 mol L-1 C6H5COONa. The Ka for C6H5COOH is 6.5 × 10-5.

Determine the molar solubility of BaF2 in a solution containing 0.0750 mol L-1 LiF. Ksp (BaF2)= 1.7 × 10-6.

What is the molar solubility of AgCl in 0.10 mol L-1 NaCN if the colourless complex ion Ag(CN)2- forms? Ksp for AgCl is 1.8 × 10-10 and Kf for Ag(CN)2- is 1.0 × 1021.

Calculate the pH of a buffer that is 0.158 mol L-1 HClO and 0.099 mol L-1 NaClO. The Ka for HClO is 2.9 × 10-8.

A 25.0 mL sample of 0.150 mol L-1 hypochlorous acid is titrated with a 0.150 mol L-1 NaOH solution. What is the pH after 26.0 mL of base is added? The Ka of hypochlorous acid is 3.0 × 10-8.

Calculate the percent ionization of nitrous acid in a solution that is 0.210 mol L-1 in nitrous acid (HNO2)and 0.290 mol L-1 in potassium nitrite (KNO2). The acid dissociation constant of nitrous acid is 4.50 × 10-4.

Which of the following solutions represents a good buffer system?

Sketch the titration curve for a diprotic acid. Make sure to label the equivalence point(s)and the relative amounts of base that were added to reach them.

A sample contains Ba3(PO4)2, CdS, AgCl, NH4Cl, and ZnS. Identify the soluble salt remaining in the solution after the addition of 6 mol L-1 HCl, followed by the addition of H2S and 0.2 mol L-1 HCl, then the addition of OH- to a pH of 8, and finally the addition of (NH4)2HPO4 with NH3.

What is the molar solubility of Mg(OH)2 in a basic solution with a pH of 12.50? Ksp for Mg(OH)2 is 5.6 × 10-12.

A buffer solution is 0.100 mol L-1 in both C6H5COOH and C6H5COOLi and has a pH of 4.19. Which of the following pH values would you expect after the addition of a small amount of a strong base?

Calculate the pH of a solution that is 0.210 mol L-1 in nitrous acid (HNO2)and 0.290 mol L-1 in potassium nitrite (KNO2). The acid dissociation constant of nitrous acid is 4.50 × 10-4.

A solution containing CaCl2 is mixed with a solution of Li2C2O4 to form a solution that is 2.1 × 10-5 mol L-1 in calcium ion and 4.75 × 10-5 mol L-1 in oxalate ion. What will happen once these solutions are mixed? Ksp (CaC2O4)= 2.3 × 10-9.

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

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 before the addition of any HBr.

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

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 200.0 mL of KOH. The Ka of HF is 3.5 × 10-4.

What is the pH of a solution made by mixing 40.00 mL of 0.100 mol L-1 HCl with 25.00 mL of 0.100 mol L-1 KOH? Assume that the volumes of the solutions are additive.

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Filters

If the pK_aof HCOOH is 3.74 and the pH of an HCOOH/HCOONabuffer solution is 3.89, which of the following is TRUE?

Calculate the pH of a solution formed by mixing 150.0 mL of 0.10 mol L^-1 C₆H₅COOH with 100.0 mL of 0.30 mol L^-1 C₆H₅COONa. The K_a for C₆H₅COOH is 6.5 × 10^-5.

Determine the molar solubility of BaF₂ in a solution containing 0.0750 mol L^-1 LiF. K_sp (BaF₂)= 1.7 × 10^-6.

What is the molar solubility of AgCl in 0.10 mol L^-1 NaCN if the colourless complex ion Ag(CN)₂^- forms? K_sp for AgCl is 1.8 × 10^-10 and K_f for Ag(CN)₂^- is 1.0 × 10²¹.

Calculate the pH of a buffer that is 0.158 mol L^-1 HClO and 0.099 mol L^-1 NaClO. The K_a for HClO is 2.9 × 10^-8.

A 25.0 mL sample of 0.150 mol L^-1 hypochlorous acid is titrated with a 0.150 mol L^-1 NaOH solution. What is the pH after 26.0 mL of base is added? The K_a of hypochlorous acid is 3.0 × 10^-8.

Calculate the percent ionization of nitrous acid in a solution that is 0.210 mol L^-1 in nitrous acid (HNO₂)and 0.290 mol L^-1 in potassium nitrite (KNO₂). The acid dissociation constant of nitrous acid is 4.50 × 10^-4.

What is the molar solubility of Mg(OH)₂ in a basic solution with a pH of 12.50? K_spfor Mg(OH)₂ is 5.6 × 10^-12.

A buffer solution is 0.100 mol L^-1 in both C₆H₅COOH and C₆H₅COOLi and has a pH of 4.19. Which of the following pH values would you expect after the addition of a small amount of a strong base?

Calculate the pH of a solution that is 0.210 mol L^-1 in nitrous acid (HNO₂)and 0.290 mol L^-1 in potassium nitrite (KNO₂). The acid dissociation constant of nitrous acid is 4.50 × 10^-4.

A solution containing CaCl₂ is mixed with a solution of Li₂C₂O₄ to form a solution that is 2.1 × 10^-5 mol L^-1 in calcium ion and 4.75 × 10^-5mol L^-1 in oxalate ion. What will happen once these solutions are mixed? K_sp (CaC₂O₄)= 2.3 × 10^-9.

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

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 before the addition of any HBr.

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 200.0 mL of KOH. The K_a of HF is 3.5 × 10^-4.

What is the pH of a solution made by mixing 40.00 mL of 0.100 mol L^-1 HCl with 25.00 mL of 0.100 mol L^-1 KOH? Assume that the volumes of the solutions are additive.