Ideal gas law
![Isotherms of an ideal gas. The curved lines represent the relationship between pressure (on the vertical, y-axis) and volume (on the horizontal, x-axis) for an ideal gas at different temperatures: lines which are farther away from the origin (that is, lines that are nearer to the top right-hand corner of the diagram) represent higher temperatures.](/Images/godic/202502/02/Ideal_gas_isotherms.svg3355.png")
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The ideal gas law is the equation of state of a hypothetical ideal gas. It is a good approximation to the behavior of many gases under many conditions, although it has several limitations. It was first stated by Émile Clapeyron in 1834 as a combination of Boyle's law, Charles' law and Avogadro's Law. The ideal gas law is often written as: