Question

A real gas obeying van der Waal equation will resemble ideal gas if the

• A. constants a and b are small
• B. a is large and b is small
• C. a is small and b is large
• D. constants a and b are large

Answer 1

Answer: (A)

constants a and b are small

Answer 2

According to van der Waal's equation, $\left( p + \frac{a}{V^2} \right)$ = RT for one mole of the gas. Obviously if a and b are small, $a/V^2$ and b can be neglected as compared to P and V and the equation reduces to PV = RT A real gas will resemble an ideal gas when constants a and b are small