Question

The enthalpy of neutralisation of a weak acid is less than that of a strong acid. The difference of the latter from the former is known as enthalpy of ionisation of the weak acid.
If true enter 1 else 0.

Answer 1

Hint: Change in enthalpy is when one equivalent of an acid one equivalent of base which undergoes a neutralisation reaction to form salt and water. It is also defined as energy realised with a formation of one mole of water.

Complete step by step solution:
Standard enthalpy change of neutralisation is the enthalpy change when an acid and a base react under standard conditions to produce 1 mole of water. Its value is always negative. Because, heat is released when an acid reacts with a base. For strong acids and bases, the enthalpy of neutralisation values are always closely similar with the values -57 and -58 KJ/mol.
We know that strong acids completely ionize in water. In case of weak acids, only partial dissociation of its ions occurs. So the enthalpy change of neutralisation will depend on enthalpy of ionisation of the acid and the reaction between the hydroxide and hydrogen ions. Tha is energy is released not only due to the dissociation of ions, but also due to breaking of hydrogen bonds. Therefore, the measured enthalpy of neutralisation is a few kJ less exothermic than with the strong acids.
Difference between the enthalpy of neutralisation of a strong acid and weak acid gives the enthalpy of ionisation of weak acid.

Therefore, the statement is true and we have to enter 1.

Note: Weak acids do not completely ionise in water. This causes variations in its enthalpy of neutralisation.