Question

The acid dissociation constant for $HC_6H_7O_6$ is $8.0 \times 10^{-5}$. If a solution contains equal concentrations of $HC_6H_7O_6$ and $C_6H_7O_6^-$, what will be the pH of the solution?

• A. 3.0
• B. 4.1
• C. 5.3
• D. 9.0

Hint:

For buffer solutions with equal concentrations of an acid and its conjugate base, the pH is the $pK_a$ of the acid.

Answer 1

The Correct Option is B

Since the solution contains equal concentrations of the acid and its conjugate base, the pH is determined using the $pK_a$ of the acid. The pH is given by the formula $pH = \dfrac{pK_a}{2} = 4.1$.