Question

Which of the following mixtures in aqueous solution acts as a buffer?

• A. $HN{O}_3+KN{O}_3$
• B. $H_{2}S{O}_4+K_{2}S{O}_4$
• C. $N{H}_{4}OH+N{H}_{4}Cl$
• D. $C{H}_{3}COOH+NaCl$

Answer 1

The correct option is C $N{H}_{4}OH+N{H}_{4}Cl$

A mixture of ammonium hydroxide and $HCl$ react to form ammonium chloride. This also contains unreacted ammonium hydroxide.

$N{H}_{4}OH+HCl\to N{H}_{4}Cl+H_{2}O$

Thus, the resulting mixture of $(N{H}_{4}OH+N{H}_{4}Cl)$ is a basic buffer solution. It contains a mixture of weak base ammonium hydroxide and its salt (ammonium chloride) with a strong acid ($HCl$).

Option A and B contain strong acid and salt of strong acid and strong base thus it does not form buffer solution,

Option D contains a mixture of weak acid and salt of strong acid and strong base thus it also does not form a buffer solution.