Question

What is the strongest acid ($p{K}_a$ value is given)?

• A. $HCOOH\left[3.77\right]$
• B. $C_6{H}_{5}COOH\left[4.22\right]$
• C. ${CH}_{3}COOH\left[4.7\right]$
• D. ${CH}_3{CH}_{2}COOH\left[4.88\right]$

Answer 1

The correct option is A $HCOOH\left[3.77\right]$

The $p{K}_a$ value indicates the strength of an acid. A lower $p{K}_a$ value indicates a stronger acid i.e, the lower value indicates the acid more fully dissociates in water.

$\therefore$ Formic acid with lower $p{K}_a$ value of $3.77$ is the strongest acid.