$(P\; +\;\frac{n^2\cdot a}{V^2})(V- n\cdot b)$$ = $$n\;R\;T $
with: $P$ Pressure $atm$ $V$ Volume $L$ $n$ Number of moles $mol$ $T$ Kelvin temperature $K$ $R$ Ideal gas constant = $0,082\;\frac{L\cdot atm}{mol\cdot K}$