Question

For a gas having extremely low molecular weight

• A. The value of $\frac{n^{2}a}{V^2}$ can be neglected compared with P
• B. The value of Z increases with increase in P
• C. The value of Z decreases with increase in P
• D. The value of $\frac{n^{2}a}{V^2}$ cannot be neglected compared with P

Answer 1

Answer: (A), (B)

The value of Z increases with increase in P

For gas having low molecular wt. the value of a is also less. So the term $\frac{a{n}^2}{V^2}$ is less and can be neglected when compared with P.
So, for one mole gas, the real gas equation reduces to:
PV = RT + Pb
$\Rightarrow \frac{PV}{RT}=1+\frac{Pb}{RT}\Rightarrow Z=1+\frac{Pb}{RT}$
Hence, Z is directly proportional to P, therefore, on increasing the value of P, Z value will also increase