Question

What is the enthalpy of neutralisation?

• A. -57.3 kJ mol${}^{-1}$.
• B. +57.3 kJ mol${}^{-1}$.
• C. 0 kJ mol${}^{-1}$.
• D. None of these

Answer 1

Answer: (A)

-57.3 kJ mol${}^{-1}$.

The standard enthalpy change of neutralization is the enthalpy change when solutions of an acid and an alkali react together under standard conditions to produce 1 mole of water.

Enthalpy change of neutralization is always measured per mole of water formed. Enthalpy changes of neutralization are always negative as heat is released when an acid and alkali react.

For reactions involving strong acids and alkalis, the values are always very closely similar, with values between -57 and -58 kJ mol${}^{-1}$. That varies slightly depending on the acid-alkali combination.

Hence, the correct option is $A$