Question 1

What is the pH of an aqueous solution that contains 0.39 M C6H5COOH and 0.14 M C6H5COONa?
K a(C6H5COOH) = 6.3×10 - 5

Accepted Answer

A)  pH = 0.409 
B)  pH = 3.76 
C)  pH = 4.65 
D)  pH = 6.29 
E)  pH = 8.65 
A)  pH = 0.409 
B)  pH = 3.76 
C)  pH = 4.65 
D)  pH = 6.29 
E)  pH = 8.65

Question 2

Consider the following equilibrium reaction:
NH₃+ H₂ O   NH ₄+ + OH - K b (NH ₃) = 1.8 10 - 5 Qualitatively, what is the effect of adding NaOH to an aqueous solution of NH₃as shown in the equilibrium reaction above?
(Use Le Chatelier s principle.)

Accepted Answer

A)  The equilibrium will shift left favoring the reactant side and the pH will drop. 
B)  The equilibrium will shift right favoring the product side and the pH will drop. 
C)  There will be no shift in the equilibrium reaction and the pH will remain constant. 
D)  The equilibrium will shift left favoring the reactant side and the pH will rise. 
E)  The equilibrium will shift right favoring the product side and the pH will rise. 
A)  The equilibrium will shift left favoring the reactant side and the pH will drop. 
B)  The equilibrium will shift right favoring the product side and the pH will drop. 
C)  There will be no shift in the equilibrium reaction and the pH will remain constant. 
D)  The equilibrium will shift left favoring the reactant side and the pH will rise. 
E)  The equilibrium will shift right favoring the product side and the pH will rise.

Question 3

Calculate the pH of a solution that is 0.78 M NH3 and 0.140 M NH4NO3. K b = 1.8×10 - 5 for NH3.

Accepted Answer

A)  4.00 
B)  10.00 
C)  4.74 
D)  9.26 
E)  13.91 
A)  4.00 
B)  10.00 
C)  4.74 
D)  9.26 
E)  13.91

Question 4

A 25.0 mL volume of 0.100 M aspartic acid (monoprotic) is titrated with 0.100 M NaOH to the equivalence point. If the pH at the equivalence point is 8.28, calculate K a for aspartic acid.

Accepted Answer

A)  1.4×10 - 4 
B)  7.3×10 - 4 
C)  5.2×10 - 9 
D)  1.9×10 - 6 
E)  1.0 
A)  1.4×10 - 4 
B)  7.3×10 - 4 
C)  5.2×10 - 9 
D)  1.9×10 - 6 
E)  1.0

Question 5

A 25.0 mL volume of a 0.200 M N2H4 solution ( K b = 1.70×10 - 6) is titrated to the equivalence point with 0.100 M HCl. What is the pH of this solution at the equivalence point?
The titration is:
N2H4 + HCl→N2H5+ + Cl -

Accepted Answer

A)  4.70 
B)  8.23 
C)  7.00 
D)  9.30 
E)  5.77 
A)  4.70 
B)  8.23 
C)  7.00 
D)  9.30 
E)  5.77

Question 6

What is the pH of the following solution?
20)0 mL of 0.50 M acetic acid ( K a = 1.8×10 - 5) is added tO5 .00 mL of 0.50 M NaOH.

Accepted Answer

A)  4.27 
B)  4.74 
C)  5.22 
D)  5.40 
E)  7.00 
A)  4.27 
B)  4.74 
C)  5.22 
D)  5.40 
E)  7.00

Question 7

If it takes 32.0 mL of 0.100 M HCl to titrate 25.0 mL of a Ba(OH)2 solution to the equivalence point, what is the molarity of the original Ba(OH)2 solution?

Accepted Answer

A)  0.128 M 
B)  3.20×10 - 2 M 
C)  0.256 M 
D)  6.40×10 - 2 M 
E)  0.100 M 
A)  0.128 M 
B)  3.20×10 - 2 M 
C)  0.256 M 
D)  6.40×10 - 2 M 
E)  0.100 M

Question 8

Which pair(s) of substances would make a suitable buffer pair combination?
I. NaOH and NaBr
II. HF and NaF
III. CH3NH3+Cl -  and CH3NH2

Accepted Answer

A)  I only 
B)  II only 
C)  III only 
D)  I and II 
E)  II and III 
A)  I only 
B)  II only 
C)  III only 
D)  I and II 
E)  II and III

Question 9

Which one of these combinations would give a buffer that would be most effective in the pH range 3.0 tO4.0?

Accepted Answer

A)  0.10 M CH3COOH, 0.10 M CH3COONa, K a = 1.8×10 - 5 
B)  0.10 M NH4Cl, 0.10 M NH3, K b = 1.8×10 - 5 
C)  0.10 M HF, 0.10 M NaF, K a = 3.54×10 - 4 
D)  0.10 M H2CO3, 0.10 M NaHCO3, K a = 4.30×10 - 7 
E)  0.10 M HCl, 0.10 NaCl 
A)  0.10 M CH3COOH, 0.10 M CH3COONa, K a = 1.8×10 - 5 
B)  0.10 M NH4Cl, 0.10 M NH3, K b = 1.8×10 - 5 
C)  0.10 M HF, 0.10 M NaF, K a = 3.54×10 - 4 
D)  0.10 M H2CO3, 0.10 M NaHCO3, K a = 4.30×10 - 7 
E)  0.10 M HCl, 0.10 NaCl

Question 10

What is the pH after the addition of 0.050 moles of NaOH to 1.00 L of a 0.500 M NH3 / 0.500 M NH4Cl buffer solution?
Assume that there is no volume change on addition of the NaOH. K b for NH3 = 1.8×10 - 5.

Accepted Answer

A)  4.74 
B)  4.66 
C)  9.34 
D)  9.17 
E)  9.53 
A)  4.74 
B)  4.66 
C)  9.34 
D)  9.17 
E)  9.53

Question 11

Oxalic acid is diprotic with p K al = 1.23 and p K a2 = 4.19. Estimate the pH of a solution of sodium hydrogen oxalate.

Accepted Answer

A)  pH = 3 
B)  pH = 5 
C)  pH = 7 
D)  pH = 9 
E)  pH = 11 
A)  pH = 3 
B)  pH = 5 
C)  pH = 7 
D)  pH = 9 
E)  pH = 11

Question 12

The following compounds have very limited solubility in water. Which of the following would dissolve in water under acidic conditions?

Accepted Answer

A)  BaCO3 
B)  BaSO4 
C)  PbSO4 
D)  AgI 
E)  CuCl 
A)  BaCO3 
B)  BaSO4 
C)  PbSO4 
D)  AgI 
E)  CuCl

Question 13

Which of the following titration curves listed below best represents a curve for the complete titration of citric acid, H3C6H5O7, a triprotic acid with a strong base such as NaOH?

Accepted Answer

A)    
B)    
C)    
D)    
E)    
A)    
B)    
C)    
D)    
E)

Question 14

Calculate the pH in a solution which is made when 20.0 mL of 0.10 M NH3 ( K b = 1.8×10 - 5) is added to 30.0 mL of 0.10 M HCl.

Accepted Answer

A)  0.02 
B)  1.70 
C)  4.57 
D)  4.74 
E)  9.25 
A)  0.02 
B)  1.70 
C)  4.57 
D)  4.74 
E)  9.25

Question 15

A solution of HCOOH ( K a = 1.8×10 - 4) and HCOO -  was submitted for chemical analysis. The results were:
[HCOOH] = 0.050 M, [HCOO - ] = 0.15 M. Calculate the pH.

Accepted Answer

A)  4.22 
B)  3.74 
C)  3.27 
D)  1.30 
E)  - 1.30 
A)  4.22 
B)  3.74 
C)  3.27 
D)  1.30 
E)  - 1.30

Question 16

Which experiment listed below would provide a titration curve that resembles the titration shown below?

Accepted Answer

A)  Titrating NH3 with standard NaOH (delivered from the burette). 
B)  Titrating NH3 with standard HCl (delivered from the burette). 
C)  Titrating H3PO4 with standard NaOH (delivered from the burette). 
D)  Titrating Na3PO4 with standard HCl (delivered from the burette). 
E)  Titrating Na3PO4 with standard NaOH (delivered from the burette). 
A)  Titrating NH3 with standard NaOH (delivered from the burette). 
B)  Titrating NH3 with standard HCl (delivered from the burette). 
C)  Titrating H3PO4 with standard NaOH (delivered from the burette). 
D)  Titrating Na3PO4 with standard HCl (delivered from the burette). 
E)  Titrating Na3PO4 with standard NaOH (delivered from the burette).

Question 17

Consider a buffer solution containing a weak acid, HX, and a salt of the weak acid's conjugate base, NaX. Under what conditions does the pH just equal the p K a of the weak acid?

Accepted Answer

A) When the p K a equals 7.0. B) When [HX] > [NaX]. C) When [HX] < [NaX]. D) When [HX] = [NaX]. E) When there is no NaX present. A) When the p K a equals 7.0. B) When [HX] > [NaX]. C) When [HX] < [NaX]. D) When [HX] = [NaX]. E) When there is no NaX present.

Question 18

What is the pH of an aqueous solution that contains 0.085 M HNO2 and 0.10 M potassium nitrite (KNO2)?
K a(HNO2) = 4.5×10 - 4

Accepted Answer

A)  pH = 3.27 
B)  pH = 3.42 
C)  pH = 4.28 
D)  pH = 4.42 
E)  pH = 7.87 
A)  pH = 3.27 
B)  pH = 3.42 
C)  pH = 4.28 
D)  pH = 4.42 
E)  pH = 7.87

Question 19

Exhibit 16-2 Consider titrating CHS1U1B13S1U1B0COOH with standard NaOH (delivered from the burette) to answer the following question(s).
-Refer to Exhibit 16-2. How would the pH be determined for the aqueous solution in the titration above at the equivalence point ?

Accepted Answer

A)  The pH would equal 7.0 at the equivalence point. 
B)  The pH is determined by the Henderson-Hasselbalch equation. 
C)  The pH is determined by taking - log[CH3COOH]original. 
D)  The pH is determined by solving for the pH of a basic salt. 
E)  The pH is determined by solving for the pH of an acidic salt. 
A)  The pH would equal 7.0 at the equivalence point. 
B)  The pH is determined by the Henderson-Hasselbalch equation. 
C)  The pH is determined by taking - log[CH3COOH]original. 
D)  The pH is determined by solving for the pH of a basic salt. 
E)  The pH is determined by solving for the pH of an acidic salt.

Question 20

What is the pH of an aqueous solution that contains 0.183 M sodium formate (NaCHO2) and 0.300 M in formic acid?
K a(HCHO2) = 1.8×10 - 4

Accepted Answer

A)  pH = 3.53 
B)  pH = 3.96 
C)  pH = 4.56 
D)  pH = 5.16 
E)  pH = 8.13 
A)  pH = 3.53 
B)  pH = 3.96 
C)  pH = 4.56 
D)  pH = 5.16 
E)  pH = 8.13

Exam 16: Reactions Between Acids and Bases

What is the pH of an aqueous solution that contains 0.39 M C6H5COOH and 0.14 M C6H5COONa? K a(C6H5COOH) = 6.3×10 - 5

Consider the following equilibrium reaction: NH₃+ H₂ O NH ₄+ + OH - K b (NH ₃) = 1.8 10 - 5 Qualitatively, what is the effect of adding NaOH to an aqueous solution of NH₃as shown in the equilibrium reaction above? (Use Le Chatelier s principle.)

Calculate the pH of a solution that is 0.78 M NH3 and 0.140 M NH4NO3. K b = 1.8×10 - 5 for NH3.

A 25.0 mL volume of 0.100 M aspartic acid (monoprotic) is titrated with 0.100 M NaOH to the equivalence point. If the pH at the equivalence point is 8.28, calculate K a for aspartic acid.

A 25.0 mL volume of a 0.200 M N2H4 solution ( K b = 1.70×10 - 6) is titrated to the equivalence point with 0.100 M HCl. What is the pH of this solution at the equivalence point? The titration is: N2H4 + HCl→N2H5+ + Cl -

What is the pH of the following solution? 20)0 mL of 0.50 M acetic acid ( K a = 1.8×10 - 5) is added tO5 .00 mL of 0.50 M NaOH.

If it takes 32.0 mL of 0.100 M HCl to titrate 25.0 mL of a Ba(OH)2 solution to the equivalence point, what is the molarity of the original Ba(OH)2 solution?

Which pair(s) of substances would make a suitable buffer pair combination? I. NaOH and NaBr II. HF and NaF III. CH3NH3+Cl - and CH3NH2

Which one of these combinations would give a buffer that would be most effective in the pH range 3.0 tO4.0?

What is the pH after the addition of 0.050 moles of NaOH to 1.00 L of a 0.500 M NH3 / 0.500 M NH4Cl buffer solution? Assume that there is no volume change on addition of the NaOH. K b for NH3 = 1.8×10 - 5.

Oxalic acid is diprotic with p K al = 1.23 and p K a2 = 4.19. Estimate the pH of a solution of sodium hydrogen oxalate.

The following compounds have very limited solubility in water. Which of the following would dissolve in water under acidic conditions?

Which of the following titration curves listed below best represents a curve for the complete titration of citric acid, H3C6H5O7, a triprotic acid with a strong base such as NaOH?

Calculate the pH in a solution which is made when 20.0 mL of 0.10 M NH3 ( K b = 1.8×10 - 5) is added to 30.0 mL of 0.10 M HCl.

A solution of HCOOH ( K a = 1.8×10 - 4) and HCOO - was submitted for chemical analysis. The results were: [HCOOH] = 0.050 M, [HCOO - ] = 0.15 M. Calculate the pH.

Which experiment listed below would provide a titration curve that resembles the titration shown below?

Consider a buffer solution containing a weak acid, HX, and a salt of the weak acid's conjugate base, NaX. Under what conditions does the pH just equal the p K a of the weak acid?

What is the pH of an aqueous solution that contains 0.085 M HNO2 and 0.10 M potassium nitrite (KNO2)? K a(HNO2) = 4.5×10 - 4

Exhibit 16-2 Consider titrating CH3COOH with standard NaOH (delivered from the burette) to answer the following question(s). -Refer to Exhibit 16-2. How would the pH be determined for the aqueous solution in the titration above at the equivalence point ?

What is the pH of an aqueous solution that contains 0.183 M sodium formate (NaCHO2) and 0.300 M in formic acid? K a(HCHO2) = 1.8×10 - 4

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What is the pH of an aqueous solution that contains 0.39 M C₆H₅COOH and 0.14 M C₆H₅COONa? K _a(C₆H₅COOH) = 6.3×10^{- 5}

Calculate the pH of a solution that is 0.78 M NH₃ and 0.140 M NH₄NO₃. K _b = 1.8×10^{- 5} for NH₃.

A 25.0 mL volume of 0.100 M aspartic acid (monoprotic) is titrated with 0.100 M NaOH to the equivalence point. If the pH at the equivalence point is 8.28, calculate K _a for aspartic acid.

A 25.0 mL volume of a 0.200 M N₂H₄ solution ( K _b = 1.70×10^{- 6}) is titrated to the equivalence point with 0.100 M HCl. What is the pH of this solution at the equivalence point? The titration is: N₂H₄ + HCl→N₂H₅⁺ + Cl^-

What is the pH of the following solution? 20)0 mL of 0.50 M acetic acid ( K _a = 1.8×10^{- 5}) is added tO₅ .00 mL of 0.50 M NaOH.

If it takes 32.0 mL of 0.100 M HCl to titrate 25.0 mL of a Ba(OH)₂ solution to the equivalence point, what is the molarity of the original Ba(OH)₂ solution?

Which pair(s) of substances would make a suitable buffer pair combination? I. NaOH and NaBr II. HF and NaF III. CH₃NH₃⁺Cl^- and CH₃NH₂

Which one of these combinations would give a buffer that would be most effective in the pH range 3.0 tO₄.0?

What is the pH after the addition of 0.050 moles of NaOH to 1.00 L of a 0.500 M NH₃ / 0.500 M NH₄Cl buffer solution? Assume that there is no volume change on addition of the NaOH. K _b for NH₃ = 1.8×10^{- 5}.

Oxalic acid is diprotic with p K _al = 1.23 and p K _a2 = 4.19. Estimate the pH of a solution of sodium hydrogen oxalate.

Which of the following titration curves listed below best represents a curve for the complete titration of citric acid, H₃C₆H₅O₇, a triprotic acid with a strong base such as NaOH?

Calculate the pH in a solution which is made when 20.0 mL of 0.10 M NH₃ ( K _b = 1.8×10^{- 5}) is added to 30.0 mL of 0.10 M HCl.

A solution of HCOOH ( K _a = 1.8×10^{- 4}) and HCOO^- was submitted for chemical analysis. The results were: [HCOOH] = 0.050 M, [HCOO^-] = 0.15 M. Calculate the pH.

Consider a buffer solution containing a weak acid, HX, and a salt of the weak acid's conjugate base, NaX. Under what conditions does the pH just equal the p K _a of the weak acid?

What is the pH of an aqueous solution that contains 0.085 M HNO₂ and 0.10 M potassium nitrite (KNO₂)? K _a(HNO₂) = 4.5×10^{- 4}

Exhibit 16-2 Consider titrating CH₃COOH with standard NaOH (delivered from the burette) to answer the following question(s). -Refer to Exhibit 16-2. How would the pH be determined for the aqueous solution in the titration above at the equivalence point ?

What is the pH of an aqueous solution that contains 0.183 M sodium formate (NaCHO₂) and 0.300 M in formic acid? K _a(HCHO₂) = 1.8×10^{- 4}