Question

A gas at 350 K and 15 bar has molar volume 20 percent smaller than that for an ideal gas under the same conditions. The correct option about the gas and its compressibility factor (Z) is:

• A. Z > 1 and attractive forces are dominant
• B. Z > 1 and repulsive forces are dominant
• C. Z < 1 and attractive forces are dominant
• D. Z < 1 and repulsive forces are dominant

Answer 1

The correct option is C Z < 1 and attractive forces are dominant

We know,
Compressibility factor (Z) = $\frac{V_{real}}{V_{ideal}}$
In the given question molar volume of the gas is 20 percent smaller than that for an ideal gas under the same conditions
$\therefore V_{real}<V_{ideal}$ ; Hence Z < 1
If Z < 1, attractive forces are dominant in the gaseous molecules and liquefaction of the gas will be easy.