Ideal Gas Law

The ideal gas law is an equation of state stating:

$$p=\rho RT$$

where:

• $\rho$ is the number density
• $R$ is the gas constant $R=N_A{k}_B$
  • $N_A=6.023\times 10^{23}$ (Avogadro’s number)
  • $k_B=1.38\times 10^{-23}\text{J}/\text{K}$
• $p$ is pressure given by $p\equiv \frac{F}{L^2}$.

Note that the pressure $p$ can be expressed in 2 ways:

1. Absolute pressure $p_{\text{abs}}$, taken relative to vacuum $p_{\text{abs}}=0$. The standard sea-level atmospheric pressure is $p_{\text{abs}}=1.013\times 10^5\text{ Pa}$
2. Gage pressure $p$ is given relative to the local atmospheric pressure: $p_{\text{abs}}=p+1.013\times 10^5\text{ Pa}$