Question

Which of the following is an example of buffer solution? Choose the correct answer from the options given below:

• A. A mixture of nitric acid and sodium nitrate
• B. A mixture of sodium hydroxide and nitric acid
• C. A mixture of acetic acid and sodium hydroxide
• D. A mixture of acetic acid and sodium acetate

Hint:

Buffer = Weak acid/base + its salt (conjugate base/acid). Think acetic acid + sodium acetate!

Answer 1

The Correct Option is D

A buffer solution is a solution that resists changes in pH when small amounts of an acid or a base are added. This occurs because a buffer solution typically consists of a weak acid and its conjugate base or a weak base and its conjugate acid.

In the options given:

• A mixture of nitric acid and sodium nitrate: This does not form a buffer solution because nitric acid is a strong acid, and strong acids do not form buffer solutions with their conjugate bases.
• A mixture of sodium hydroxide and nitric acid: This does not form a buffer solution as it is a neutralization reaction between a strong base and a strong acid.
• A mixture of acetic acid and sodium hydroxide: This can form a solution where acetic acid is partially neutralized to form sodium acetate, but it won't function as a buffer until all reactants are in the correct stoichiometric proportions.
• A mixture of acetic acid and sodium acetate: This is a classic example of a buffer solution. Acetic acid (a weak acid) and sodium acetate (its conjugate base) together form a buffer solution that can resist changes in pH.

Therefore, the correct answer is: A mixture of acetic acid and sodium acetate.