Explain the difference between the terms heat and enthalpy.

  • Heat (q): Heat refers to the transfer of energy from one body or system to another due to a temperature difference. It is a form of energy in transit. Heat flows from a higher temperature object to a lower temperature object and depends on the mass, specific heat, and temperature difference. Heat is not a state function; its value depends on the process and the path taken to transfer the energy.

  • Enthalpy (H): Enthalpy is a thermodynamic property of a system that represents the total heat content at constant pressure. It includes both the internal energy of the system (U), which is the energy required to create a system, and the product of the pressure and volume (PV), which accounts for the work done by the system on its surroundings. The enthalpy change (ΔH) represents the heat absorbed or released during a process at constant pressure. Unlike heat, enthalpy is a state function, meaning its value depends only on the current state of the system, not on how it arrived there.

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