What is the Difference Between Enthalpy and Heat?
🆚 Go to Comparative Table 🆚The main difference between enthalpy and heat lies in their definitions and the conditions under which they are measured. Here are the key distinctions:
- Heat: Heat is the transfer of energy due to a temperature difference between two systems. It is a form of energy that flows from one system to its surroundings due to a difference in temperature. Heat is not a state function, meaning that the change in heat cannot be measured additively, as you would need to know the "path" taken to get a proper measurement.
- Enthalpy: Enthalpy is the change in the amount of heat in a system at constant pressure. It is the sum of a system's internal energy and is the product of the system's volume and pressure. Enthalpy is a state function, meaning that the change in enthalpy can be determined additively. Enthalpy is also equivalent to the heat flow as measured at constant pressure.
In summary, heat is the energy transferred between two systems due to a temperature difference, while enthalpy is the change in the amount of heat in a system at constant pressure. Enthalpy is a state function, whereas heat is not.
Comparative Table: Enthalpy vs Heat
The main differences between enthalpy and heat are summarized in the following table:
| Enthalpy | Heat |
|---|---|
| Enthalpy is a state function that measures the total energy of a system, including the energy associated with the system's volume and pressure. | Heat is a form of energy that is transferred from a hot object to a cold object, resulting in a change in temperature. |
| Enthalpy is a state function, meaning it depends only on the initial and final states of a system. | Heat is a process variable that depends on the path taken to transfer energy. |
| Enthalpy change (ΔH) is often used in chemical reactions to describe the heat absorbed or released during the reaction, providing information about the heat released or absorbed by the system. | Heat is a measure of energy transfer between two objects or systems. |
| Entropy is not an intrinsic property of a system, and we cannot measure it directly, so we have to calculate it through equations. | Heat can be measured directly as a temperature change. |
In summary, enthalpy represents the total energy of a system, while heat is the transfer of energy. Enthalpy is a state function that depends only on the initial and final states of a system, whereas heat is a process variable that depends on the path taken to transfer energy.
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- Heat Capacity vs Specific Heat
- Heat Transfer vs Thermodynamics
- Thermal Energy vs Temperature
- Work vs Heat
- Light Energy vs Heat Energy
- Heat of Solution vs Heat of Reaction
- Specific Heat Capacity vs Heat Capacity
- Thermochemistry vs Thermodynamics
- Latent Heat vs Specific Heat
- Bond Enthalpy vs Lattice Enthalpy
- Heat of Formation vs Heat of Reaction