Question

What among the following solutions will be the most efficient buffer?

• A. $0.1M$ ${CH}_{3}COONa+0.01M$ ${CH}_{3}COOH$
• B. $0.1M$ ${NH}_{4}Cl+0.1M$ ${NH}_{4}OH$
• C. $0.001M$ $HCOOH+0.002M$ $HCOONa$
• D. All of the above

Answer 1

The correct option is B $0.1M$ ${NH}_{4}Cl+0.1M$ ${NH}_{4}OH$

Buffer capacity of solution is maximum under the following conditions :

[Salt] $=$ [Acid] (in acid buffer)

[Salt] $=$ [Base] (in base buffer)

A) $\left[{CH}_{3}COONa\right]\ne \left[{CH}_{3}COOH\right]$

B) $\left[{NH}_{4}Cl\right]=\left[{NH}_{4}OH\right]$

C) $\left[HCOOH\right]\ne \left[HCOONa\right]$

Now, the condition $B$ involving equal concentrations of salt and base should be most efficient buffer.