Question

When $36.5g$ of $HCl$ is added to $1L$ of an acidic buffer solution, its $pH$ changes from 4 to 3. The buffer capacity of the buffer is:

• A. 1
• B. 2
• C. 3
• D. 4

Answer 1

The correct option is A 1

Buffer capacity :
It is defined as the moles of a strong acid or strong base required to change the pH of 1 L of a buffer by one unit.

Moles of HCl is : $\frac{\text{Mass}}{\text{Molar mass}}=\frac{36.5}{36.5}=1mol$

$\text{Buffer capacity}=\frac{\text{Number of moles of acid or base added to a 1L buffer}}{\text{Change in pH}}\text{Buffer capacity}=\frac{1}{4-3}=1$