The heat of reaction, also known as the enthalpy change of reaction, is the amount of heat energy absorbed or released during a chemical reaction. It is a measure of the difference in energy between the reactants and products.
The heat of reaction is calculated by subtracting the energy of the reactants from the energy of the products. This difference can be determined experimentally using a calorimeter, or it can be calculated using thermodynamic data.
The heat of reaction is affected by the nature of the reactants and products, the temperature and pressure of the reaction, and the presence of a catalyst. Changes in these factors can alter the amount of heat absorbed or released during the reaction.
Q, or reaction quotient, is a measure of the relative amounts of reactants and products in a system at a given moment. The heat of reaction is directly related to Q, as it is a measure of the change in energy between reactants and products. As Q changes, so does the heat of reaction.
The heat of reaction is a key factor in determining the spontaneity of a reaction. If the heat of reaction is negative, meaning heat is released, the reaction is exothermic and spontaneous. If the heat of reaction is positive, meaning heat is absorbed, the reaction is endothermic and non-spontaneous. However, other factors such as entropy and Gibbs free energy must also be considered in determining the spontaneity of a reaction.
