Question

Consider the equation $Z=\frac{PV}{nRT}$ ; which of the following statement is correct?

• A. When $Z>1$, real gases are easier to compress than the ideal gas.
• B. When $Z=1$, real gases get compressed easily.
• C. When $Z>1$, real gases are difficult to compress.
• D. When $Z=1$, real gases are difficult to compress.

Answer 1

Answer: (C)

When $Z>1$, real gases are difficult to compress.

The deviation from ideal behaviour is expressed by the factor $Z$ known as compressibility factor in the ideal gas equation. $Z$ is expressed as $Z=PV/nRT$

In case of real, $PV=nRT$, therefore $Z\ne 1$

When $Z>1$, it is a positive deviation. It shows that the gas is less compressible expected from ideal behaviour.