Question

Which of the following will function as buffer?

• A. $Na{H}_{2}P{O}_4+N{a}_{2}HP{O}_4$
• B. $C_6{H}_{5}N{H}_2+C_6{H}_{5}N{H}_3^{+}C{l}^{-}$
• C. $N{H}_{4}Cl+N{H}_{4}OH$
• D. All of the above.

Answer 1

The correct option is D All of the above.

Buffer solution: A buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base or weak base and its conjugate acid.
Acidic buffer solution: Acidic buffer are solution of a mixture of weak acid and salt of its conjugate base of that acid with a strong base.
Basic bufer solution: Basic buffer are solution of a mixture of weak base and salt of its conjugate acid of that base with a strong acid.
a) $(Na{H}_{2}P{O}_4+N{a}_{2}HP{O}_4)$ is acidic buffer because it is a mixture of weak acid $\left(Na{H}_{2}P{O}_4\right)$ and its salt$\left(N{a}_{2}HP{O}_4\right)$ with strong base $\left(NaOH\right)$.
b) $(C_6{H}_{5}N{H}_2+C_6{H}_{5}N{H}_3^{+}C{l}^{-})$ is basic buffer because it is a mixture of weak base $\left(C_6{H}_{5}N{H}_2\right)$ and its salt$\left(C_6{H}_{5}N{H}_3^{+}C{l}^{-}\right)$ with strong acid $\left(HCl\right)$.
c) $(N{H}_{4}Cl+N{H}_{4}OH)$ is basic buffer because it is a mixture of weak base $\left(N{H}_{4}OH\right)$ and its salt$\left(N{H}_{4}Cl\right)$ with strong acid $\left(HCl\right)$.
So a, b and c are buffer solutions.