Assertion :Heat of neutralisation of HF (aq.) a weak acid, with NaOH (aq.) is more than 13.7 kcal, in an exothermic reaction. Reason: Because some heat is lost in the ionisation of a weak acid.

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion

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Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion

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Assertion is correct but Reason is incorrect

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Both Assertion and Reason are incorrect

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Solution

The correct option is C Assertion is correct but Reason is incorrect
The average enthalpy of neutralization of any strong acid by a strong base is found to be –57.7. This is because strong acids and strong bases are completely ionized in aqueous solutions. The aqueous solution of one gram equivalent of all strong acids contains the same number of $H^{+}$ ions. Similarly, aqueous solution of one gram equivalent of all strong bases also contains same number of $O H^{-}$ . The neutralization reactions between strong acids and strong bases in aqueous solutions involve simply the combination of $H^{+}$ ions (from an acid) and $O H^{-}$ ions (from a base) to form unionized water molecules.
When strong acid and a weak base or weak acid and a strong
base or weak acid and weak base are mixed in equivalent amounts, the heat evolved or change in enthalpy is less than -57.7.

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