Question 1

Which of the following combinations will produce a buffer solution when mixed in water?

Accepted Answer

CH3COOH and CH3COONa

Question 2

A buffer solution is most effective when:

Accepted Answer

The concentrations of weak acid and its conjugate base are equal and high

Question 3

What is the pH of a buffer solution that is 0.10 M in acetic acid (pKa = 4.74) and 0.10 M in sodium acetate?

Accepted Answer

$$\mathrm{pH} = 4.74$$

Question 4

Which equation is the Henderson-Hasselbalch equation?

Accepted Answer

$$\mathrm{pH} = \mathrm{p}K_a + \log \frac{[A^-]}{[HA]}$$

Question 5

A buffer is overwhelmed when:

Accepted Answer

The amount of strong acid or base added exceeds the buffer's capacity

Question 6

Calculate the pH of a buffer solution that is 0.50 M in ammonia ($$\mathrm{p}K_b = 4.75) $$and 0.20 M in ammonium chloride.

Accepted Answer

$$\mathrm{pH} = 9.43$$

Question 7

Which of the following best describes why blood pH must be tightly regulated?

Accepted Answer

Blood pH affects the oxygen-carrying capacity of hemoglobin

Question 8

If you add 0.01 mol of NaOH to a buffer containing 0.10 mol HA and 0.10 mol A-, what is the new ratio of $$[A^-]/[HA]$$?

Accepted Answer

$$\frac{0.11}{0.09}$$

Question 9

Which of the following is NOT a property of a buffer solution?

Accepted Answer

It is made from a strong acid and its conjugate base

Question 10

A buffer is most effective within what pH range relative to its pKa?

Accepted Answer

$$\mathrm{p}K_a \pm 1$$

Question 11

Which of the following compartments has the highest pH according to the provided data?

Accepted Answer

Pancreas secretions

Question 12

What is the correct expression for the acid dissociation constant $$K_a$$ for a weak acid $$HA$$?

Accepted Answer

$$K_a = \frac{[H^+][A^-]}{[HA]}$$

Question 13

Which of the following would NOT be a good buffer system for maintaining a pH near 7.4?

Accepted Answer

Acetic acid and sodium acetate ($$\mathrm{p}K_a = 4.74)$$

Question 14

Which of the following statements about buffer capacity is TRUE?

Accepted Answer

Buffer capacity increases as the concentrations of acid and conjugate base increase

Question 15

A buffer solution is prepared by mixing 0.10 mol of formic acid ($$HCHO_2) $$and 0.10 mol of sodium formate ($$NaCHO_2) in 1.0 L of $$water. What will happen to the pH if a small amount of HCl is added?

Accepted Answer

The pH will decrease slightly, but remain close to the original value

Question 16

Which of the following best explains why a buffer made from a weak acid and its conjugate base resists changes in pH?

Accepted Answer

The weak acid neutralizes added base and the conjugate base neutralizes added acid

Question 17

Which of the following is a correct statement about the conjugate base of a strong acid?

Accepted Answer

It is a very weak base

Question 18

A buffer solution is prepared with 0.18 mol HA and 0.02 mol A-. After adding 0.01 mol of strong base, which statement is correct?

Accepted Answer

The pH will increase, and the percent pH change will be greater than for a buffer with equal amounts of HA and A-

Question 19

Which of the following is a limitation of the Henderson-Hasselbalch equation?

Accepted Answer

It is inaccurate when the concentrations of acid and base are very low

Buffers: Capacity, pH, and Applications in General Chemistry

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