👉 The term "enthalpy" is defined as the amount of heat required to change the state or temperature of a substance from one state to another. It is often used in chemistry and physics, particularly in chemical reactions and thermodynamics. In simple terms, an enthalpy is a measure of how much energy (heat) is needed to convert one form of matter into another. For example, when you heat water to 100°C (about 212°F), the water will