Hess law can help us to obtain the enthalpy of a series of reactions by summation. The missing enthalpy of this reaction is −198kJ.
<h3>What is Hess law?</h3>
According to the Hess law of constant heat summation, the enthalpy of a sequence of reactions can be obtained as the sum of the enthalpies of all the reactions.
Now looking at all the reavtion written here in order to obtain the missing enthalpy, we conclude that the missing enthalpy is −198kJ.