Ideal Gas Law

up:: 034 MOC Atmospheric Physics

The ideal gas law is

$$pV=nRT$$

where $R$ is the universal gas constant, and $n$ number of moles of a given gas.

It can also be written with respect to densities $\rho$, since

$$n=\frac{m}{M}$$

where $m$ is the (macro) gas mass and $M$ the (micro) molar mass of the gas molecules.¹ Thus, it can also be written as

$$p=\rho \underset{:=\frac{R}{M}}{\underbrace{R_{sp}}}T$$

where $R_{sp}$ is the specific gas constant (for a given gas).

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References

• WALLACE, John Michael; HOBBS, Peter Victor. Atmospheric science: an introductory survey. 2nd ed ed. Amsterdam Paris: Academic press, 2006.

Footnotes

1. For water ($H_{2}O$), it is $18$: $16$ for $O$, $1$ for each $H$. ↩