The Enthalpy of Neutralization of any strong acid by any strong base is virtually constant at $-57.1\text{ kJ/mol}$ (or $-13.7\text{ kcal/mol}$).

• Reason: Strong acids and bases are completely dissociated in aqueous solution.
• Net ionic equation: $H^{+}(aq)+O{H}^{-}(aq)\to H_{2}O(l)$
• Since the actual process is simply the formation of water from its ions, the heat released remains the same regardless of the specific identities of the strong acid and base.