Question

Is the change in enthalpy of a reaction always equal to heat transfer?

Answer 1

1. The amount of heat energy that is transferred in a chemical system at constant pressure is known as the enthalpy change $\mathbf{(}\mathbf{∆}\mathit{H}\mathbf{)}$.
2. The amount of heat in a chemical system is called enthalpy. Energy is absorbed or released in the form of heat during chemical reactions.
3. The overall enthalpy of the system changes when the thermal energy is transferred from the system. The overall enthalpy of a process increases when energy is absorbed but falls when energy is released.
4. We can measure the enthalpy change $\mathbf{(}\mathbf{∆}\mathit{H}\mathbf{)}$ that occurs in a chemical reaction, but we cannot directly measure the overall enthalpy of a system.

Therefore, it would be incorrect to assume that enthalpy merely has an effect only on heat transport.