Question

Ionization constants $K_a$ for formic acid and acetic acid are $17.7\times {10}^{-5}$ and $1.77\times {10}^{-5}$. Which acid is stronger and how many times the other if equimolar concentrations of the two are taken?

Answer 1

Given: $K_a$ for $HCOOH>K_a$ for $C{H}_{3}COOH$. Hence formic acid is stronger.

Further, $\frac{\text{Strength of}HCOOH}{\text{Strength of}C{H}_{3}COOH}=\sqrt{\frac{K_{HCOOH}}{K_{C{H}_{3}COOH}}}=\sqrt{10}=3.16$ times.