The specific heat capacity, c s, is a measure of how much heat is required to increase the temperature of 1 g of a material by 1 ☌.Ī material with a higher specific heat capacity requires more energy to raise its temperature and vice versa. Q is equal to the mass of the substance times its specific heat capacity and the change in temperature. So, how do we use ΔT to calculate ΔH? At constant pressure, ΔH is equal to the heat flow, Q. So, we can then assume that the temperature change is due to the heat change in the reaction. We can assume that no energy is transferred into or out of the sample cell because it is insulated. As the reaction proceeds inside of the insulated cell, the temperature changes and we are able to measure ΔT. A simplified calorimeter, like the one we have here, consists of an insulated sample cell with a stirrer and a thermometer. We can measure the enthalpy change of a reaction using an isolated system like a calorimeter. If ΔH is negative, the reaction is exothermic and releases heat to the surroundings.
If ΔH is positive, the reaction is endothermic and absorbs heat from the surroundings.
Thus, the ΔH of a reaction is calculated by subtracting the sum of the enthalpies of the reactants from the sum of the enthalpies of the products. Enthalpy is used to describe chemical reactions, where the enthalpy change, ΔH, tells us how much heat is absorbed or released during a chemical reaction.Įnthalpy is a state function, meaning that the change is independent of the path and only takes into account the initial and final state. One of the most important thermodynamic properties is enthalpy, which indicates the heat energy transferred by a process at constant pressure. Thermodynamics is the study of heat and its relation to energy and work.