Question

Why is maximum temperature change achieved when the reactants are in their stoichiometric ratio?

Answer 1

When the reactants are taken in accordance with the stoichiometry of the reaction, all the reactants are consumed completely and energy change is also in accordance with the enthalpy of reaction. However, if any of the reactants is taken in lesser amount then reaction will not go to completion that is some amount of other reactant will remain unreacted. The energy change which would have taken place if whole of the reactant would have been consumed will lessen from the enthalpy of the reaction. Hence, highest energy is released when reactants are taken in accordance with the stoichiometry of the reaction