Question

van der Waals equation for one mole of $CO_2$ gas at low pressure will be

• A. $\left(P+\frac{a}{V^{2}}\right)V=RT$
• B. $P\left(V-b\right)=RT-\frac{a}{V^{2}}$
• C. $P=\frac{RT}{V-b}$
• D. $P=\left(\frac{RT}{V-b}-\frac{a}{V^{2}}\right)$

Answer 1

Answer: (A)

$\left(P+\frac{a}{V^{2}}\right)V=RT$

Answer 2

van der Waals equation for one mole of $CO_2$ gas is $\left[P+\frac{a}{V^{2}}\right]\left[V-b\right] = RT$ At low pressure, $V$ is high hence $(V - b) \approx V$. $\therefore\left(P+\frac{a}{V^{2}}\right)V = RT$