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Fluids

Isochoric process

Isochoric stems from the Greek words ισος (isos = equal) and χωρος (choros = volume). An isochoric process is a thermodynamic process in which the volume stays constant.
Consider for example a quantity of an ideal gas in a container under a piston which is fixed and cannot move.
When that system is heated then, according to Gay-Lussac's law (first discovered by Amontons), the pressure of the gas increases, whereas the volume V stays constant. Since the piston is fixed no work can be performed by the gas.

The above process is shown in the following pressure-volume diagram where we consider an increase in pressure from P₁ to P₂.



The total amount of work W_1→2 done by the gas can easily be determined from (remember ΔV=0)

W_1→2 = P×ΔV = 0

In the above process all heat is used for internal changes in the gas: its temperature has risen.

kinetic energy