Q. Carboxylic acids readily dissolve in aqueous sodium bicarbonate, liberating carbon dioxide. Which one of the following is correct?
A) Free carboxylic acid and its conjugate base are of comparable stability.
B) The free carboxylic acid is more stable than its conjugate base.
C) The conjugate base of the carboxylic acid is more stable than the free carboxylic acid.
D) The conjugate acid of the carboxylic acid is more stable than the free carboxylic acid.
Explanation
(c)
$RCOOH + NaHCO_{3} \rightleftharpoons RCOONa + H_{2}O + CO_{2}$
or $RCOOH + HCO_{3}^{-} \rightleftharpoons RCOO^{-} + H_{2}O + CO_{2}$
Conjugate base, $RCOO^{-}$ is more stable. That is why equilibrium shifts in the forward direction.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.