Heat exchanged between system and surroundings at constant volume temperature for a chemical reaction is given by

Heat exchanged between system and surroundings at constant volume temperature for a chemical reaction is given by ΔU. The heat of Reaction at Constant Volume: The difference between the sum of internal energies of products and the sum of internal energies of reactants at a given temperature and constant volume is called the heat of reaction at the constant volume at a given temperature. It is denoted by ΔE. ΔU = ΔH = ∑ΔU Products – ∑ΔU Reactants