Question

The enthalpy of neutralization of $NaOH$ with acetic acid is $55kJ$ and with $HCl$ is $57.1kJ$ . This happens because:

• A. some heat is required for complete ionisation of acetic acid
• B. acetic acid is an organic acid
• C. acetic acid is less soluble in water
• D. acetic acid is a weak acid and required lesser alkali

Answer 1

Answer: (A)

The enthalpy of neutralization of weak acid with strong base is always lesser than the strong acid with strong base. Hence, the enthalpy of neutralization of $NaOH$ with $C{H}_{3}COOH$ is $55kJ$ and with $HCl$ is $57.1kJ$. This is due to that weak acid is not completely dissociated. Hence, some of heat is utilised for complete ionisation of weak acid, i.e., $C{H}_{3}COOH$.