An isochoric process is a thermodynamic process in which the volume remains constant throughout. Because the volume doesn’t change, the system cannot do any pressure-volume work (since work done by a gas is W=PΔVW = P \Delta V, and here ΔV=0\Delta V = 0).

Key points about an isochoric process:

• Volume VV = constant.
• No work is done by the system (W=0W = 0).
• Any heat added or removed changes the internal energy and pressure (and temperature) but not the volume.
• Often called an isochoric or isovolumetric process.

Example:

Heating a gas in a rigid, sealed container — since the container doesn’t expand, the gas volume stays fixed.