Question

When $73g$ of $HCl$ is added to $1L$ of an acidic buffer solution, its $pH$ changes from 3.4 to 2.9. The buffer capacity of the buffer is:

• A. 7
• B. 8
• C. 4
• D. 9

Answer 1

The correct option is C 4

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 : $\frac{\text{Mass}}{\text{Molar mass}}=\frac{73}{36.5}=2mol$

$\text{Buffer capacity}=\frac{\text{Number of moles of acid or base added to a 1L buffer}}{\text{Change in pH}}\text{Buffer capacity}=\frac{2}{3.4-2.9}=4$