Paper: CSIR-NET June 2013 · Subject: Physical Chemistry · Chapter: Thermodynamics · Topic: Free Energy Equilibria · Marks: 2 · Difficulty: Medium
A system consists of gaseous $\mathrm{H}_{2}, \mathrm{O}_{2}, \mathrm{H}_{2} \mathrm{O}$ and $\mathrm{CO}_{2}$ where the amount of $\mathrm{CO}_{2}$ is specified and the equilibrium constant for the reaction $2 \mathrm{H}_{2}(\mathrm{g})+\mathrm{O}(\mathrm{g}) \rightleftharpoons 2 \mathrm{H}_{2} \mathrm{O}(\mathrm{g})$ is known. The number of degrees of freedom of the system is
(a)2
(b)3
(c)4
(d)5
Answer
Answer: B ✓ checked by 4AB · confidence medium
Explanation
Four species and one equilibrium give C = 3; with one phase F = 3 − 1 + 2 = 4, and fixing the amount of CO₂ removes one more: F = 3.