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Ideal gas laws
Beginner
Boyle, Charles and Gay-Lussac laws relate P, V and T.
At low density gases follow simple laws linking pressure, volume and temperature, summarised by the ideal gas equation.
Aerosol cans explode when heated.
Valid for real gases at low pressure and high temperature.
In more detail
Ideal gases obey simple laws relating pressure, volume, temperature and amount. Real gases approach ideal behaviour at low pressure and high temperature.
Real-world uses
- Engineers model air in engines and compressors as ideal gases.
- Gas cylinders and scuba tanks are designed using gas laws.
- Divers, balloonists and gas-filled syringes all behave in ways that the gas laws predict.
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Frequently asked questions
When is a gas ideal?
At low pressure and high temperature, where molecular interactions are small.
Which gas law is most important?
The ideal gas equation, PV = nRT, which combines the others.
Which gas law should I use first?
If the temperature is constant, use Boyle's law. If the pressure is constant, use Charles's law, or combine them into PV = nRT.
Related topics in Heat & Thermodynamics
Newton's law of cooling · Wien's displacement law · Blackbody radiation · Boyle's law · Charles's law · Ideal gas equation