Here’s a explanation:
Enthalpy (H)
- Enthalpy is a measure of the total heat content of a system.
- It includes the system’s internal energy plus the energy required to push aside the surroundings (pressure × volume).
- In simple words, it tells us how much heat a system can give or absorb at constant pressure.
How Enthalpy Changes
- When a reaction or process occurs at constant pressure, the heat absorbed or released equals the change in enthalpy.
- Exothermic: Heat is released → Enthalpy decreases
- Endothermic: Heat is absorbed → Enthalpy increases
Measuring Enthalpy
- Direct measurement of enthalpy is not possible, but changes in enthalpy (ΔH) can be measured using:
- Calorimetry – measures heat released or absorbed in chemical reactions.
- Standard enthalpy values – using tables of enthalpies of formation, combustion, or reaction.
In short:
- Enthalpy is the heat content of a system at constant pressure.
- We usually measure it as the heat absorbed or released during a process.