Question

At low pressure, Van der Waal's equation is reduced to $[P+\frac{a}{V^2}]V=RT$. The compressibility factor can be given as:

• A. $1-\frac{a}{RTV}$
• B. $1-\frac{RTV}{a}$
• C. $1+\frac{a}{RTV}$
• D. $1+\frac{RTV}{a}$

Answer 1

The correct option is A $1-\frac{a}{RTV}$

The reduced van der Waal's equation is: $[P+\frac{a}{V^2}]$ V = RT
$⟹PV+\frac{a}{V}=RT$ or $\frac{PV}{RT}+\frac{a}{RTV}=1$
$⟹\frac{PV}{RT}=(1-\frac{a}{RTV})=z$