Question

Correct option regarding a container containing 1 mol of a gas in 22.4 litre container at 273 K is

• A. If compressibility factor (Z) > 1 then 'P' will be less than 1 atm.
• B. If compressibility factor (Z) > 1 then 'P' will be greater than 1 atm.
• C. If 'b' dominates, pressure will be less than 1 atm.
• D. If 'a' dominates, pressure will be greater than 1 atm.

Answer 1

Answer: (B)

If compressibility factor (Z) > 1 then 'P' will be greater than 1 atm.

Answer 2

The given conditions are STP for an ideal gas, where P = 1 atm. For real gases, $P_{actual} = Z \times P_{ideal}$. If $Z > 1$, then $P_{actual} > 1$ atm. The van der Waals equation is $(P + \frac{an^2}{V^2})(V - nb) = nRT$. 'a' term (attraction) leads to $Z < 1$ (lower pressure). 'b' term (repulsion) leads to $Z > 1$ (higher pressure). Therefore, if 'b' dominates, $P > 1$ atm. If 'a' dominates, $P < 1$ atm.