How this calculator works
For a fixed amount of ideal gas held at one temperature, pressure times volume stays constant. Slow compression with heat removal can approximate this process. Use absolute pressure, obtained by adding atmospheric pressure to a gauge reading. The optional initial-state modes use p1 V1 = n R T and the exact SI gas constant.
Formula
p1 V1 = p2 V2; pV = nRT for the initial-state temperature and amount modes.
Worked example
A gas at 100000 Pa and 0.02 m³ occupies 0.01 m³ at 200000 Pa. Starting at 300000 Pa and 0.004 m³, expansion to 0.012 m³ gives 100000 Pa.
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Frequently asked questions
What stays constant?
Temperature and amount of gas.
When does the ideal model lose accuracy?
Near condensation or at high density, intermolecular forces and finite molecular size become important.
Does this describe rapid compression?
Usually not. Rapid compression can raise temperature; an adiabatic model may fit better.