Question

Mixing of non-reacting ideal gases at constant pressure is generally accompanied by:

• A. decrease in entropy
• B. increase in entropy
• C. change in enthalpy
• D. increase in free energy

Answer 1

The correct option is A decrease in entropy

Using the relation of entropy of mixing of constant pressure.

$△S_{mix}=-2303R{n}_{1}log{x}_1+n_{2}log{x}_2$

where $n=$ mole of each component

$x=$ fraction of mole of each component

Since Mole fraction, $\chi =\frac{n_1}{n_1+n_2+...}$ are always less than one.

$\Rightarrow △S_{mix}=positive$ i.e $△S_{mix}$ is increasing