Question 1

Which is the correct mathematical expression for the molar solubility (x) in moles per liter of Fe3(PO4)2?

Accepted Answer

A)  12x3 
B)  108x5 
C)  6x2 
D)  6x5 
E)  5x6 
A)  12x3 
B)  108x5 
C)  6x2 
D)  6x5 
E)  5x6

Question 2

A certain indicator HIn has a pKa of 9.00, and a color change becomes visible when 7.00% of it is In-. At what pH is this color change visible?

Accepted Answer

A)  6.15 
B)  7.88 
C)  10.2 
D)  3.85 
E)  none of these 
A)  6.15 
B)  7.88 
C)  10.2 
D)  3.85 
E)  none of these

Question 3

Calculate the pH when 200.0 mL of a 1.00 M solution of H2A (Ka1 = 1.0 F1F1F1S1F1F1F10 10-6, Ka2 = 1.0 F1F1F1S1F1F1F10 10-10) is titrated with the following volumes of 1.00 M NaOH. 100.0 mL of 1.00 M NaOH

Accepted Answer

A)  3.35 
B)  8.00 
C)  3.00 
D)  6.00 
E)  none of these 
A)  3.35 
B)  8.00 
C)  3.00 
D)  6.00 
E)  none of these

Question 4

Silver chromate, Ag2CrO4, has a Ksp of 9.0 F1F1F1S1F1F1F10 10-12. Calculate the solubility, in moles per liter, of silver chromate.

Accepted Answer

A)  7.8 F1F1F1S1F1F1F10 10-5 M 
B)  9.5 F1F1F1S1F1F1F10 10-7 M 
C)  9.8 F1F1F1S1F1F1F10 10-5 M 
D)  1.9 F1F1F1S1F1F1F10 10-12 M 
E)  1.3 F1F1F1S1F1F1F10 10-4 M 
A)  7.8 F1F1F1S1F1F1F10 10-5 M 
B)  9.5 F1F1F1S1F1F1F10 10-7 M 
C)  9.8 F1F1F1S1F1F1F10 10-5 M 
D)  1.9 F1F1F1S1F1F1F10 10-12 M 
E)  1.3 F1F1F1S1F1F1F10 10-4 M

Question 5

A solution is prepared by mixing hydrazoic acid (HN3) and NaN3 and then allowed to come to equilibrium. Upon addition of sulfuric acid

Accepted Answer

A)  More HN3 will be formed 
B)  more NaN3 will be formed 
C)  More N   will be formed 
D)  Both A and B 
E)  Impossible to answer without knowing equilibrium concentrations 
A)  More HN3 will be formed 
B)  more NaN3 will be formed 
C)  More N   will be formed 
D)  Both A and B 
E)  Impossible to answer without knowing equilibrium concentrations

Question 6

What volume of 0.0100 M NaOH must be added to 1.00 L of 0.0500 M HOCl to achieve a pH of 8.00? Ka for HOCl is 3.5 F1F1F1S1F1F1F10 10-8.

Accepted Answer

A)  1.2 L 
B)  1.0 L 
C)  3.9 L 
D)  5.0 L 
E)  none of these 
A)  1.2 L 
B)  1.0 L 
C)  3.9 L 
D)  5.0 L 
E)  none of these

Question 7

Consider the following information about the diprotic acid ascorbic acid (HS1U1B12S1U1B0As for short, molar mass = 176.1).   The titration curve for disodium ascorbate, NaS1U1B12S1U1B0As, with standard HCl is shown below:  
-What is the pH at point I (V1/2 HCl added)?

Accepted Answer

A)  7.95 
B)  12.39 
C)  10 
D)  11.79 
E)  none of these 
A)  7.95 
B)  12.39 
C)  10 
D)  11.79 
E)  none of these

Question 8

What combination of substances will give a buffered solution that has a pH of 5.05? Assume each pair of substances is dissolved in 5.0 L of water. (Kb for NH3 = 1.8 F1F1F1S1F1F1F10 10-5; Kb for C5H5N = 1.7 F1F1F1S1F1F1F10 10-9)

Accepted Answer

A)  1.0 mol C5H5N and 1.5 mol C5H5NHCl 
B)  1.0 mol NH3 and 1.5 mol NH4Cl 
C)  1.5 mol NH3 and 1.0 mol NH4Cl 
D)  1.5 mol C5H5N and 1.0 mol C5H5NHCl 
E)  none of these 
A)  1.0 mol C5H5N and 1.5 mol C5H5NHCl 
B)  1.0 mol NH3 and 1.5 mol NH4Cl 
C)  1.5 mol NH3 and 1.0 mol NH4Cl 
D)  1.5 mol C5H5N and 1.0 mol C5H5NHCl 
E)  none of these

Question 9

The solubility, in moles per liter, of Ag2CrO4 is 1.3 F1F1F1S1F1F1F10 10-4 M at 25°C. Calculate Ksp for this compound.

Accepted Answer

A)  2.3 F1F1F1S1F1F1F10 10-13 
B)  6.1 F1F1F1S1F1F1F10 10-9 
C)  8.8 F1F1F1S1F1F1F10 10-12 
D)  4.7 F1F1F1S1F1F1F10 10-13 
E)  8.8 F1F1F1S1F1F1F10 10-3 
A)  2.3 F1F1F1S1F1F1F10 10-13 
B)  6.1 F1F1F1S1F1F1F10 10-9 
C)  8.8 F1F1F1S1F1F1F10 10-12 
D)  4.7 F1F1F1S1F1F1F10 10-13 
E)  8.8 F1F1F1S1F1F1F10 10-3

Question 10

Calculate the pH at the equivalence point for the titration of 1.0 M ethylamine, C2H5NH2, by 1.0 M perchloric acid, HClO4. (pKb for C2H5NH2 = 3.25)

Accepted Answer

A)  6.05 
B)  2.24 
C)  2.09 
D)  5.38 
E)  5.53 
A)  6.05 
B)  2.24 
C)  2.09 
D)  5.38 
E)  5.53

Question 11

In a solution prepared by adding excess PbI2(s) [Ksp = 1.4 F1F1F1S1F1F1F10 10-8] to water, [I-] at equilibrium is

Accepted Answer

A)  2.4 F1F1F1S1F1F1F10 10-3 mol/L. 
B)  1.5 F1F1F1S1F1F1F10 10-3 mol/L. 
C)  8.4 F1F1F1S1F1F1F10 10-5 mol/L. 
D)  3.0 F1F1F1S1F1F1F10 10-3 mol/L. 
E)  1.2 F1F1F1S1F1F1F10 10-3 mol/L. 
A)  2.4 F1F1F1S1F1F1F10 10-3 mol/L. 
B)  1.5 F1F1F1S1F1F1F10 10-3 mol/L. 
C)  8.4 F1F1F1S1F1F1F10 10-5 mol/L. 
D)  3.0 F1F1F1S1F1F1F10 10-3 mol/L. 
E)  1.2 F1F1F1S1F1F1F10 10-3 mol/L.

Question 12

For ammonia, Kb is 1.8 F1F1F1S1F1F1F10 10-5 . To make a buffered solution with pH 10.0, the ratio of NH4Cl to NH3 must be

Accepted Answer

A)  1.8 : 1. 
B)  0.18 : 1. 
C)  1 : 1.8. 
D)  1 : 0.18. 
E)  none of these 
A)  1.8 : 1. 
B)  0.18 : 1. 
C)  1 : 1.8. 
D)  1 : 0.18. 
E)  none of these

Question 13

How many moles of Ca(NO3)2 must be added to 1.0 L of a 0.12 M HF solution to begin precipitation of CaF2(s)? For CaF2, Ksp = 4.0 F1F1F1S1F1F1F10 10-11.

Accepted Answer

A)  2.8 F1F1F1S1F1F1F10 10-9 mol 
B)  3.3 F1F1F1S1F1F1F10 10-10 mol 
C)  5.4 F1F1F1S1F1F1F10 10-7 mol 
D)  4.8 F1F1F1S1F1F1F10 10-12 mol 
E)  5.8 F1F1F1S1F1F1F10 10-13 mol 
A)  2.8 F1F1F1S1F1F1F10 10-9 mol 
B)  3.3 F1F1F1S1F1F1F10 10-10 mol 
C)  5.4 F1F1F1S1F1F1F10 10-7 mol 
D)  4.8 F1F1F1S1F1F1F10 10-12 mol 
E)  5.8 F1F1F1S1F1F1F10 10-13 mol

Question 14

A 200.0-mL sample of the weak acid HS1U1B13S1U1B0A (0.100 M) is titrated with 0.200 M NaOH. What are the major species at each of the following points in the titration? (Water is always assumed to be a major species.)
-After 350.0 mL of 0.200 M NaOH is added

Accepted Answer

A)  A3- 
B)  HA2-, A3- 
C)  HA2- 
D)  OH-, A3- 
E)  H2A-, HA2- 
A)  A3- 
B)  HA2-, A3- 
C)  HA2- 
D)  OH-, A3- 
E)  H2A-, HA2-

Question 15

A 65.5-mL sample of 0.14 M HNO2 (Ka = 4.0 F1F1F1S1F1F1F10 10-4) is titrated with 0.11 M NaOH. What is the pH after 26.8 mL of NaOH has been added?

Accepted Answer

A)  10.28 
B)  7.00 
C)  3.72 
D)  2.91 
E)  3.07 
A)  10.28 
B)  7.00 
C)  3.72 
D)  2.91 
E)  3.07

Question 16

Calculate the solubility of Ag2SO4 [Ksp = 1.2 F1F1F1S1F1F1F10 10-5] in a 2.0 M AgNO3 solution.

Accepted Answer

A)  6.0 F1F1F1S1F1F1F10 10-6 mol/L 
B)  1.2 F1F1F1S1F1F1F10 10-5 mol/L 
C)  3.0 F1F1F1S1F1F1F10 10-6 mol/L 
D)  1.4 F1F1F1S1F1F1F10 10-2 mol/L 
E)  none of these 
A)  6.0 F1F1F1S1F1F1F10 10-6 mol/L 
B)  1.2 F1F1F1S1F1F1F10 10-5 mol/L 
C)  3.0 F1F1F1S1F1F1F10 10-6 mol/L 
D)  1.4 F1F1F1S1F1F1F10 10-2 mol/L 
E)  none of these

Question 17

Calculate the solubility of Ca3(PO4)2(s) (Ksp = 1.3 F1F1F1S1F1F1F10 10-32) in a 1.0 F1F1F1S1F1F1F10 10-2 M Ca(NO3)2 solution.

Accepted Answer

A)  3.16 F1F1F1S1F1F1F10 10-12 mol/L 
B)  5.7 F1F1F1S1F1F1F10 10-14 mol/L 
C)  6.2 F1F1F1S1F1F1F10 10-7 mol/L 
D)  1.6 F1F1F1S1F1F1F10 10-14 mol/L 
E)  none of these 
A)  3.16 F1F1F1S1F1F1F10 10-12 mol/L 
B)  5.7 F1F1F1S1F1F1F10 10-14 mol/L 
C)  6.2 F1F1F1S1F1F1F10 10-7 mol/L 
D)  1.6 F1F1F1S1F1F1F10 10-14 mol/L 
E)  none of these

Question 18

The concentration of Mg2+ in seawater is 0.052 M. At what pH will 99% of the Mg2+ be precipitated as the hydroxide? (Ksp for Mg(OH)2 = 8.9 F1F1F1S1F1F1F10 10-12)

Accepted Answer

A)  6.50 
B)  9.22 
C)  10.12 
D)  8.35 
E)  4.86 
A)  6.50 
B)  9.22 
C)  10.12 
D)  8.35 
E)  4.86

Question 19

You have two salts, AgX and AgY, with very similar Ksp values. You know that Ka for HX is much greater than Ka for HY. Which salt is more soluble in acidic solution?

Accepted Answer

A)  AgY 
B)  This cannot be determined from the information given. 
C)  They are equally soluble in acidic solution. 
D)  AgX 
A)  AgY 
B)  This cannot be determined from the information given. 
C)  They are equally soluble in acidic solution. 
D)  AgX

Question 20

A titration of 100.0 mL of 1.00 M malonic acid (HS1U1B12S1U1B0A) was done with 1.00 M NaOH. For malonic acid, KS1U1B1a1S1U1B0 = 1.49 F1F1F1S1F1F1F10 10S1U1P1-S1S1P0S1U1P12S1S1P0, KS1U1B1a2S1U1B0 = 2.03 F1F1F1S1F1F1F10 10S1U1P1-S1S1P0S1U1P16S1S1P0.
-Calculate [H+] after 300.0 mL of 1.00 M NaOH has been added.

Accepted Answer

A)  1.00 F1F1F1S1F1F1F10 10-7 M 
B)  4.00 F1F1F1S1F1F1F10 10-14 M 
C)  1.41 F1F1F1S1F1F1F10 10-10 M 
D)  1.00 M 
E)  none of these 
A)  1.00 F1F1F1S1F1F1F10 10-7 M 
B)  4.00 F1F1F1S1F1F1F10 10-14 M 
C)  1.41 F1F1F1S1F1F1F10 10-10 M 
D)  1.00 M 
E)  none of these

Which is the correct mathematical expression for the molar solubility (x) in moles per liter of Fe₃(PO₄)₂?

A certain indicator HIn has a pK_a of 9.00, and a color change becomes visible when 7.00% of it is In^-. At what pH is this color change visible?

Calculate the pH when 200.0 mL of a 1.00 M solution of H₂A (K_a1 = 1.0  10^-⁶, K_a2 = 1.0  10^-¹⁰) is titrated with the following volumes of 1.00 M NaOH. 100.0 mL of 1.00 M NaOH

Silver chromate, Ag₂CrO₄, has a K_sp of 9.0  10^-¹². Calculate the solubility, in moles per liter, of silver chromate.

A solution is prepared by mixing hydrazoic acid (HN₃) and NaN₃ and then allowed to come to equilibrium. Upon addition of sulfuric acid

What volume of 0.0100 M NaOH must be added to 1.00 L of 0.0500 M HOCl to achieve a pH of 8.00? K_a for HOCl is 3.5  10^-⁸.

Consider the following information about the diprotic acid ascorbic acid (H₂As for short, molar mass = 176.1). The titration curve for disodium ascorbate, Na₂As, with standard HCl is shown below: -What is the pH at point I (V₁/2 HCl added)?

What combination of substances will give a buffered solution that has a pH of 5.05? Assume each pair of substances is dissolved in 5.0 L of water. (K_b for NH₃ = 1.8  10^-⁵; K_b for C₅H₅N = 1.7  10^-⁹)

The solubility, in moles per liter, of Ag₂CrO₄ is 1.3  10^-⁴ M at 25°C. Calculate K_sp for this compound.

Calculate the pH at the equivalence point for the titration of 1.0 M ethylamine, C₂H₅NH₂, by 1.0 M perchloric acid, HClO₄. (pK_b for C₂H₅NH₂ = 3.25)

In a solution prepared by adding excess PbI₂(s) [K_sp = 1.4  10^-⁸] to water, [I^-] at equilibrium is

For ammonia, K_b is 1.8  10^-⁵ . To make a buffered solution with pH 10.0, the ratio of NH₄Cl to NH₃ must be

How many moles of Ca(NO₃)₂ must be added to 1.0 L of a 0.12 M HF solution to begin precipitation of CaF₂(s)? For CaF₂, K_sp = 4.0  10^-¹¹.

A 200.0-mL sample of the weak acid H₃A (0.100 M) is titrated with 0.200 M NaOH. What are the major species at each of the following points in the titration? (Water is always assumed to be a major species.) -After 350.0 mL of 0.200 M NaOH is added

A 65.5-mL sample of 0.14 M HNO₂ (K_a = 4.0  10^-⁴) is titrated with 0.11 M NaOH. What is the pH after 26.8 mL of NaOH has been added?

Calculate the solubility of Ag₂SO₄ [K_sp = 1.2  10^-⁵] in a 2.0 M AgNO₃ solution.

Calculate the solubility of Ca₃(PO₄)₂(s) (K_sp = 1.3  10^-³²) in a 1.0  10^-² M Ca(NO₃)₂ solution.

The concentration of Mg²⁺ in seawater is 0.052 M. At what pH will 99% of the Mg²⁺ be precipitated as the hydroxide? (K_sp for Mg(OH)₂ = 8.9  10^-¹²)

You have two salts, AgX and AgY, with very similar K_sp values. You know that K_a for HX is much greater than K_a for HY. Which salt is more soluble in acidic solution?

A titration of 100.0 mL of 1.00 M malonic acid (H₂A) was done with 1.00 M NaOH. For malonic acid, K_a1 = 1.49  10^-², K_a2 = 2.03  10^-⁶. -Calculate [H⁺] after 300.0 mL of 1.00 M NaOH has been added.

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Exam 8: Applications of Aqueous Equilibria