1. Measurement of heat change at constant pressure can be done in a coffee cup calorimeter.
2. We know that ∆H = qp (at constant P) and therefore, heat absorbed or evolved, qp at constant pressure is also called the heat of reaction or enthalpy of reaction, ∆Hr
3. in an exoihermic reaction, heat is evolved, and system loses heat to the surroundings.
Therefore, qp will be negative and ∆Hr will also be negative.
4. Similarly in an endothermic reaction, heat is absorbed, qp is positive and ∆Hr will also be positive.
