Question 1

During a titration, 60.0 mL of 0.010 M NaOH is added to 35.0 mL of 0.020 M HCl solution. What is the pH of the resulting solution?

Accepted Answer

A)  1.70 
B)  12.00 
C)  2.98 
D)  5.41 
E)  4.05 
A)  1.70 
B)  12.00 
C)  2.98 
D)  5.41 
E)  4.05

Question 2

Which of the following is a polyprotic acid relative to water?

Accepted Answer

A)  NH3 
B)  H2SO4 
C)  CH4 
D)  Na3PO4 
E)  H2O 
A)  NH3 
B)  H2SO4 
C)  CH4 
D)  Na3PO4 
E)  H2O

Question 3

What is the pH of a solution of 25.0 mL of 0.250 M HNO3 after the addition oF40.0 mL of 0.300 M KOH?

Accepted Answer

A)  1.02 
B)  0.60 
C)  12.95 
D)  13.25 
E)  13.45 
A)  1.02 
B)  0.60 
C)  12.95 
D)  13.25 
E)  13.45

Question 4

Exhibit 16-1 Consider the equilibrium reaction below to answer the following question(s). HNO₂ + H₂ O   H₃O + + NO₂ 1 - K a (HNO₂ ) = 4.5 10 - 4
-Refer to Exhibit 16-1. What is the effect of adding NaNO₂ to an aqueous solution of HNO₂ as shown in the equilibrium reaction above?

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 5

What is the molarity of Ba(OH)2 solution if 65.0 mL of 0.0500 M HCl is required to titrate 35.00 mL of the Ba(OH)2 solution?

Accepted Answer

A)  3.25×10 - 3 M 
B)  9.28×10 - 2 M 
C)  4.64×10 - 2 M 
D)  2.69×10 - 3 M 
E)  1.69×10 - 2 M 
A)  3.25×10 - 3 M 
B)  9.28×10 - 2 M 
C)  4.64×10 - 2 M 
D)  2.69×10 - 3 M 
E)  1.69×10 - 2 M

Question 6

In the titration of 0.100 M HCl with the titrant 0.100 M NaOH, what species are present at the equivalence point?

Accepted Answer

A)  HCl only 
B)  NaOH only 
C)  NaCl only 
D)  NaOH and NaCl 
E)  HCl and NaCl 
A)  HCl only 
B)  NaOH only 
C)  NaCl only 
D)  NaOH and NaCl 
E)  HCl and NaCl

Question 7

Consider the ionization of hydrofluoric acid as follows:
HF + H₂ O   H₃O + + F 1 - What is the effect of adding the common ion, F - (source:
NaF), to this equilibrium system?

Accepted Answer

A)  The equilibrium shifts to the right and the pH lowers. 
B)  The equilibrium shifts to the left and the pH lowers. 
C)  The equilibrium shifts to the right and the pH rises. 
D)  The equilibrium shifts to the left and the pH rises. 
E)  Nothing happens. The pH remains constant and the equilibrium does not shift in either direction. 
A)  The equilibrium shifts to the right and the pH lowers. 
B)  The equilibrium shifts to the left and the pH lowers. 
C)  The equilibrium shifts to the right and the pH rises. 
D)  The equilibrium shifts to the left and the pH rises. 
E)  Nothing happens. The pH remains constant and the equilibrium does not shift in either direction.

Question 8

Calculate the amount of ammonium chloride (NH4Cl) that must be added to 1.0 L of 0.10 M NH3 ( K b = 1.8×10 - 5) to prepare a buffer of pH 9.00.

Accepted Answer

A)  0.10 mole 
B)  0.056 mole 
C)  0.18 mole 
D)  5.6×10 - 5 mole 
E)  buffer cannot be made 
A)  0.10 mole 
B)  0.056 mole 
C)  0.18 mole 
D)  5.6×10 - 5 mole 
E)  buffer cannot be made

Question 9

A sample of 100 mL of 0.10 M acid HA ( K a = 1.0×10 - 5) is titrated with standard 0.100 M KOH. How many mL of KOH will have been added when the pH in the titration flask is 5.00?

Accepted Answer

A)  0 
B)  10 
C)  100 
D)  50 
E)  25 
A)  0 
B)  10 
C)  100 
D)  50 
E)  25

Question 10

What is the pH of an aqueous solution that is 0.55 M HNO2 and 0.75 M KNO2?
K a(HNO2) = 7.1×10 - 4

Accepted Answer

A)  pH = 3.01 
B)  pH = 3.28 
C)  pH = 3.63 
D)  pH = 6.94 
E)  pH = 7.56 
A)  pH = 3.01 
B)  pH = 3.28 
C)  pH = 3.63 
D)  pH = 6.94 
E)  pH = 7.56

Question 11

A sample of 50.0 mL of 0.10 M NH3 ( K b = 1.8×10 - 5) is titrated with 0.10 M HCl. Calculate the pH at the equivalence point.

Accepted Answer

A)  7.00 
B)  5.28 
C)  2.87 
D)  11.13 
E)  1.00 
A)  7.00 
B)  5.28 
C)  2.87 
D)  11.13 
E)  1.00

Question 12

Exhibit 16-3 Consider the Titration curve below for the titration of a weak acid ,CH ₃COOH , with a strong base , NaOH, to answer the following question(s). CH ₃COOH + NaOH CH ₃COONa + H₂ O  
Refer to Exhibit 16-3. What approach listed below would be used to solve for the pH at the equivalence point on this titration curve?

Accepted Answer

A)  The pH at the equivalence point for a weak acid equals 7.0. 
B)  The pH equals the p K a of the weak acid at the equivalence point. 
C)  The pH at the equivalence point can be determined by substituting the original molar concentration of the weak acid into the equation: pH = - log[HA]. 
D)  The Henderson-Hasselbalch equation can be used to solve for the pH at the equivalence point. 
E)  The pH at the equivalence point must be solved as a problem of equilibrium involving a basic salt. 
A)  The pH at the equivalence point for a weak acid equals 7.0. 
B)  The pH equals the p K a of the weak acid at the equivalence point. 
C)  The pH at the equivalence point can be determined by substituting the original molar concentration of the weak acid into the equation: pH = - log[HA]. 
D)  The Henderson-Hasselbalch equation can be used to solve for the pH at the equivalence point. 
E)  The pH at the equivalence point must be solved as a problem of equilibrium involving a basic salt.

Question 13

A buffer was prepared by mixing 0.60 moles of HF and 0.40 moles of NaF in enough water to make 1.00 L of solution. What is the pH of this solution?
K a = 3.5×10 - 4 for HF.

Accepted Answer

A)  10.72 
B)  3.48 
C)  3.58 
D)  10.42 
E)  3.28 
A)  10.72 
B)  3.48 
C)  3.58 
D)  10.42 
E)  3.28

Question 14

A 0.40 gram sample of NaOH (molar mass = 40.0 g/mol) was completely neutralized witH₆2.5 mL of H₂ SO₄solution. Assume the chemical equation is:
H₂ SO₄(aq) + 2 NaOH (aq) Na2 SO₄(aq) + 2 H₂ O (   ) The molarity of the H₂ SO₄solution was:

Accepted Answer

A)  0.080 M 
B)  0.16 M 
C)  0.62 M 
D)  6.4 M 
E)  3.2 M 
A)  0.080 M 
B)  0.16 M 
C)  0.62 M 
D)  6.4 M 
E)  3.2 M

Question 15

The titration of a weak acid, HA ( K a = 1.0×10 - 4), with NaOH requires 40.0 mL to reach the equivalence point. In order to calculate the pH of the system after 20 mL of NaOH is added, the best strategy is to recognize that the system is

Accepted Answer

A)  a strong acid 
B)  a weak acid 
C)  a buffer 
D)  neutral 
E)  a weak base 
A)  a strong acid 
B)  a weak acid 
C)  a buffer 
D)  neutral 
E)  a weak base

Question 16

Which of the following would not make a suitable buffer pair?

Accepted Answer

A)  NH4Cl/NH3 
B)  HNO3/NaNO3 
C)  NaHCO3/Na2CO3 
D)  H3PO4/KH2PO4 
E)  HCN/NaCN 
A)  NH4Cl/NH3 
B)  HNO3/NaNO3 
C)  NaHCO3/Na2CO3 
D)  H3PO4/KH2PO4 
E)  HCN/NaCN

Question 17

Calculate the pH of a solution made by mixing 20.00 mL of 0.300 M HCl and 50.00 mL of 0.100 M NaOH and diluting to a final volume of 1.00 L.

Accepted Answer

A)  3.00 
B)  2.22 
C)  2.30 
D)  - 1.18 
E)  0.52 
A)  3.00 
B)  2.22 
C)  2.30 
D)  - 1.18 
E)  0.52

Question 18

A 25.0 mL portion of 0.0500 M HCl was added to 10.0 mL of 0.0250 M NaOH. Calculate the pH of the resulting solution.

Accepted Answer

A)  12.54 
B)  1.54 
C)  3.00 
D)  12.06 
E)  1.30 
A)  12.54 
B)  1.54 
C)  3.00 
D)  12.06 
E)  1.30

Question 19

A buffer solution maintains a constant pH level to a certain extent when a strong base such as NaOH is added. Which of the following buffer solutions has the greatest buffering capacity to consume added NaOH?

Accepted Answer

A)  0.5 M HF/1.0 M NaF 
B)  0.5 M HF/1.5 M NaF 
C)  1.0 M HF/0.5 M NaF 
D)  1.0 M HF/1.5 M NaF 
E)  1.5 M HF/0.5 M NaF 
A)  0.5 M HF/1.0 M NaF 
B)  0.5 M HF/1.5 M NaF 
C)  1.0 M HF/0.5 M NaF 
D)  1.0 M HF/1.5 M NaF 
E)  1.5 M HF/0.5 M NaF

Question 20

Consider the buffer pair, NH4Cl/NH3. What can be stated about the relative proportions of this buffer pair if the pH of an aqueous solution of this pair is adjusted to 12.00 and the p K a for NH4+ equals 9.25?

Accepted Answer

A)  This buffer solution contains relatively more NH4+ than NH3. 
B)  This buffer solution contains relatively more NH3 than NH4+. 
C)  This buffer solution contains equal concentrations of NH4+ and NH3. 
D)  More information is needed to determine the relative proportion of each member. 
A)  This buffer solution contains relatively more NH4+ than NH3. 
B)  This buffer solution contains relatively more NH3 than NH4+. 
C)  This buffer solution contains equal concentrations of NH4+ and NH3. 
D)  More information is needed to determine the relative proportion of each member.

Exam 16: Reactions Between Acids and Bases

During a titration, 60.0 mL of 0.010 M NaOH is added to 35.0 mL of 0.020 M HCl solution. What is the pH of the resulting solution?

Which of the following is a polyprotic acid relative to water?

What is the pH of a solution of 25.0 mL of 0.250 M HNO3 after the addition oF40.0 mL of 0.300 M KOH?

Exhibit 16-1 Consider the equilibrium reaction below to answer the following question(s). HNO₂ + H₂ O H₃O + + NO₂ 1 - K a (HNO₂ ) = 4.5 10 - 4 -Refer to Exhibit 16-1. What is the effect of adding NaNO₂ to an aqueous solution of HNO₂ as shown in the equilibrium reaction above?

What is the molarity of Ba(OH)2 solution if 65.0 mL of 0.0500 M HCl is required to titrate 35.00 mL of the Ba(OH)2 solution?

In the titration of 0.100 M HCl with the titrant 0.100 M NaOH, what species are present at the equivalence point?

Consider the ionization of hydrofluoric acid as follows: HF + H₂ O H₃O + + F 1 - What is the effect of adding the common ion, F - (source: NaF), to this equilibrium system?

Calculate the amount of ammonium chloride (NH4Cl) that must be added to 1.0 L of 0.10 M NH3 ( K b = 1.8×10 - 5) to prepare a buffer of pH 9.00.

A sample of 100 mL of 0.10 M acid HA ( K a = 1.0×10 - 5) is titrated with standard 0.100 M KOH. How many mL of KOH will have been added when the pH in the titration flask is 5.00?

What is the pH of an aqueous solution that is 0.55 M HNO2 and 0.75 M KNO2? K a(HNO2) = 7.1×10 - 4

A sample of 50.0 mL of 0.10 M NH3 ( K b = 1.8×10 - 5) is titrated with 0.10 M HCl. Calculate the pH at the equivalence point.

A buffer was prepared by mixing 0.60 moles of HF and 0.40 moles of NaF in enough water to make 1.00 L of solution. What is the pH of this solution? K a = 3.5×10 - 4 for HF.

A 0.40 gram sample of NaOH (molar mass = 40.0 g/mol) was completely neutralized witH₆2.5 mL of H₂ SO₄solution. Assume the chemical equation is: H₂ SO₄(aq) + 2 NaOH (aq) Na2 SO₄(aq) + 2 H₂ O ( ) The molarity of the H₂ SO₄solution was:

The titration of a weak acid, HA ( K a = 1.0×10 - 4), with NaOH requires 40.0 mL to reach the equivalence point. In order to calculate the pH of the system after 20 mL of NaOH is added, the best strategy is to recognize that the system is

Which of the following would not make a suitable buffer pair?

Calculate the pH of a solution made by mixing 20.00 mL of 0.300 M HCl and 50.00 mL of 0.100 M NaOH and diluting to a final volume of 1.00 L.

A 25.0 mL portion of 0.0500 M HCl was added to 10.0 mL of 0.0250 M NaOH. Calculate the pH of the resulting solution.

A buffer solution maintains a constant pH level to a certain extent when a strong base such as NaOH is added. Which of the following buffer solutions has the greatest buffering capacity to consume added NaOH?

Consider the buffer pair, NH4Cl/NH3. What can be stated about the relative proportions of this buffer pair if the pH of an aqueous solution of this pair is adjusted to 12.00 and the p K a for NH4+ equals 9.25?

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What is the pH of a solution of 25.0 mL of 0.250 M HNO₃ after the addition oF₄0.0 mL of 0.300 M KOH?

What is the molarity of Ba(OH)₂ solution if 65.0 mL of 0.0500 M HCl is required to titrate 35.00 mL of the Ba(OH)₂ solution?

Calculate the amount of ammonium chloride (NH₄Cl) that must be added to 1.0 L of 0.10 M NH₃ ( K _b = 1.8×10^{- 5}) to prepare a buffer of pH 9.00.

A sample of 100 mL of 0.10 M acid HA ( K _a = 1.0×10^{- 5}) is titrated with standard 0.100 M KOH. How many mL of KOH will have been added when the pH in the titration flask is 5.00?

What is the pH of an aqueous solution that is 0.55 M HNO₂ and 0.75 M KNO₂? K _a(HNO₂) = 7.1×10^{- 4}

A sample of 50.0 mL of 0.10 M NH₃ ( K _b = 1.8×10^{- 5}) is titrated with 0.10 M HCl. Calculate the pH at the equivalence point.

A buffer was prepared by mixing 0.60 moles of HF and 0.40 moles of NaF in enough water to make 1.00 L of solution. What is the pH of this solution? K _a = 3.5×10^{- 4} for HF.

A 0.40 gram sample of NaOH (molar mass = 40.0 g/mol) was completely neutralized witH₆2.5 mL of H₂ SO₄solution. Assume the chemical equation is: H₂ SO₄(aq) + 2 NaOH (aq) Na₂ SO₄(aq) + 2 H₂ O ( ) The molarity of the H₂ SO₄solution was:

The titration of a weak acid, HA ( K _a = 1.0×10^{- 4}), with NaOH requires 40.0 mL to reach the equivalence point. In order to calculate the pH of the system after 20 mL of NaOH is added, the best strategy is to recognize that the system is

Consider the buffer pair, NH₄Cl/NH₃. What can be stated about the relative proportions of this buffer pair if the pH of an aqueous solution of this pair is adjusted to 12.00 and the p K _a for NH₄⁺ equals 9.25?