Question

Which one of the following is basic buffer solution?

• A. $CH_3COOH + CH_3COONa$
• B. $CH_3COOH + NH_4Cl$
• C. $NH_4OH + NH_4Cl$
• D. $CH_3COONa + NH_4OH$

Answer 1

Answer: (C)

$NH_4OH + NH_4Cl$

Answer 2

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