The enthalpy change for the reaction of titanium metal with gaseous iodine is given by the following thermochemical equation: 2 Ti(s) + 3 I2(g) → 2 TiI3(s) ΔH rxn = −839 kJ What is the enthalpy change for the reaction below? TiI3(s) → Ti(s) + 3/2 I2(g)

Answer : The enthalpy change for the reaction is, 419.5 kJ

Explanation :

According to Hess’s law of constant heat summation, the heat absorbed or evolved in a given chemical equation is the same whether the process occurs in one step or several steps.

The given chemical reaction is,

Now we have to determine the enthalpy change for the reaction below:

By reversing and then dividing the reaction by 2, we get the enthalpy change for the reaction.

The expression will be:

Therefore, the enthalpy change for the reaction is, 419.5 kJ