Question

Which one of the following is basic buffer solution?

• A. $C{H}_{3}COOH+C{H}_{3}COONa$
• B. $C{H}_{3}COOH+N{H}_{4}Cl$
• C. $N{H}_{4}OH+N{H}_{4}Cl$
• D. $C{H}_{3}COONa+N{H}_{4}OH$

Answer 1

Answer: (C)

$N{H}_{4}OH+N{H}_{4}Cl$ is a buffer mixture of a weak base and its salt
This mixture contains undissociated $N{H}_{4}OH$ as well as $N{H}_4^{+}$ and $C{l}^{-}$ ions
If a strong acid is added, $H^{+}$ ions added are neutralised by base $N{H}_{4}OH$
$H^{+}+N{H}_{4}OH\to H_{2}O+N{H}_4^{+}$
If a strong base is added, the $O{H}^{-}$ ions added are neutralised by $N{H}_4^{+}$ ions forming very slightly dissociated $N{H}_{4}OH$