AP Chemistry Practice Quiz: Properties of Buffers
Written by AP Content Team, Verified for 2026 AP Exams, Last updated: May 2026
Test your understanding with short quizzes. This quiz has 7 questions to check your progress.
Question 1 of 7
All Questions (7)
A) To significantly increase the pH of a solution.
B) To significantly decrease the pH of a solution.
C) To stabilize the pH of a solution.
D) To completely neutralize any added acid or base.
Correct Answer: C
The content explicitly states that the ability of a buffer is to 'stabilize pH'. It resists large changes in pH but does not necessarily increase, decrease, or completely neutralize it.
A) A strong acid and a strong base.
B) A large concentration of a conjugate acid and its base.
C) A large concentration of water and a salt.
D) A small concentration of a weak acid only.
Correct Answer: B
The text specifies that 'A buffer solution contains a large concentration of both a conjugate acid and its base.' This combination is required for the buffer to function.
A) The conjugate acid.
B) The conjugate base.
C) Both the acid and base components simultaneously.
D) The water in the solution.
Correct Answer: B
The provided content states that 'the conjugate base reacts with added acid.' This reaction consumes the added H+ ions, preventing a significant drop in pH.
A) The added base reacts with the conjugate base component of the buffer.
B) The added base reacts with the conjugate acid component of the buffer.
C) The added base is neutralized by the water molecules.
D) The added base causes the conjugate acid to dissociate.
Correct Answer: B
As stated in the text, 'The conjugate acid reacts with added base.' This reaction neutralizes the added hydroxide ions, preventing a large increase in pH.
A) Having a large concentration of only a conjugate acid allows the buffer to react with added base, stabilizing pH.
B) Having a large concentration of only a conjugate base allows the buffer to react with added acid, stabilizing pH.
C) The presence of both a conjugate acid and its base allows the buffer to react with either an added base or an added acid, respectively.
D) The concentration of the buffer components is irrelevant to its ability to stabilize pH.
Correct Answer: C
The text explains that the buffer's ability to stabilize pH comes from the fact that it contains both species: the conjugate acid to react with added base and the conjugate base to react with added acid. Both are necessary for the buffer to work against either type of addition.
A) To ensure the solution has a very low initial pH.
B) To ensure the solution has a very high initial pH.
C) To provide a sufficient amount of reactive species to handle the addition of acid or base without being depleted.
D) To make the solution more dilute and less reactive.
Correct Answer: C
A large concentration of the conjugate acid and base ensures there is enough of each to react with any added acid or base. If the concentrations were small, the buffer components would be quickly used up, and the buffer would lose its ability to stabilize pH.
A) The HPO₄²⁻ reacts with the added OH⁻.
B) The H₂PO₄⁻ reacts with the added OH⁻.
C) Both components react with the added OH⁻.
D) The system cannot stabilize pH against the addition of a base.
Correct Answer: B
In the conjugate pair H₂PO₄⁻/HPO₄²⁻, H₂PO₄⁻ is the conjugate acid and HPO₄²⁻ is the conjugate base. According to the text, the conjugate acid reacts with an added base. Therefore, H₂PO₄⁻ will react with the added OH⁻ to stabilize the pH.