Real gases closely follow the relation between pressure (P), volume per unit mass(v) and Temperature (T)
1
\(\left( {P + \frac{a}{{{V^2}}}} \right)\left( {v + b} \right) = RT\)
2
\(\left( {P + \frac{a}{{{V^2}}}} \right)\left( {v - b} \right) = RT\)
3
\(\left( {P - \frac{a}{{{V^2}}}} \right)\left( {v + b} \right) = RT\)
4
\(\left( {P - \frac{a}{{{V^2}}}} \right)\left( {v - b} \right) = RT\)