AP Chemistry: 8.7 - 8.11 Check for Understanding

A buffer solution is best described as a solution that:

• Completely neutralizes added acids and bases

• Maintains a constant pH regardless of conditions

• Resists changes in pH when small amounts of acid or base are added

• Contains only strong acids and strong bases

Which combination would form a buffer solution?

• HCl and NaCl

• NaOH and NaCl

• NH₃ and NH₄⁺

• HNO₃ and NaOH

Which real-world system acts as a buffer?

• Distilled water

• Ocean water with excess NaCl

• Human blood

• Solid sodium hydroxide

Why do HA and A⁻ both remain in solution in a buffer system?

• They completely neutralize one another

• They are both strong electrolytes

• They are weak and rarely react with water

• They precipitate out of solution

When a small amount of strong base (OH⁻) is added to a buffer, it is primarily consumed by:

• Water

• The conjugate base (A⁻)

• The weak acid (HA)

• The solvent

When a small amount of strong acid (H⁺) is added to a buffer, it reacts primarily with:

• Water

• The weak acid (HA)

• The conjugate base (A⁻)

• The solvent

The behavior of a buffer when stressed by added acid or base is best explained by:

• Collision theory

• Le Châtelier’s principle

• Hess’s law

• The ideal gas law

Buffer capacity refers to a buffer’s ability to:

• Maintain a pH of exactly 7

• Resist pH change indefinitely

• Neutralize any amount of acid or base

• Resist a change in pH greater than 1

Which change would increase the buffer capacity without changing the pH?

• Adding only HA

• Adding only A⁻

• Increasing both [HA] and [A⁻] by the same factor

• Diluting the buffer with water

A buffer contains more moles of A⁻ than HA. Which addition will cause the greatest change in pH?

• A small amount of strong acid

• A small amount of strong base

• Equal amounts of acid and base

• No addition will change the pH