Question

Describe isothermal process and derive expression for work done, change in internal energy, heat transfer and change in enthalpy

Answer 1

It is not generally true that ΔU=0 in an isothermal process.

An ideal gas by definition has no interactions between particles, no intermolecular forces, so pressre change at constant temperature does not change internal energy.

Real gases have intermolecular interactions, attractions between molecules at low pressure and repulsion at high pressure. Their internal energy changes with change in pressure, even if temperature is constant.

For an ideal gas, in an isothermal process, ΔU=0=Q−W, so Q=W.

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