Q15 · CSIR NET Chemistry, June 2014
Paper: CSIR NET June 2014 · Subject: Physical Chemistry · Chapter: Thermodynamics · Topic: Thermodynamics – General · Marks: 2 · Difficulty: Medium
Two phases $\alpha$ and $\beta$ of a species are in equilibrium. The correct relations observed among the variables, $\mathrm{T}, \mathrm{p}$ and $\mu$ are
(a)$T_{\alpha}=T_{\beta} ; p_{\alpha} \neq p_{\beta} ; \mu_{\alpha}=\mu_{\beta}$
(b)$T_{\alpha} \neq T_{\beta} ; p_{\alpha}=p_{\beta} ; \mu_{\alpha}=\mu_{\beta}$
(c)$T_{\alpha}=T_{\beta} ; p_{\alpha}=p_{\beta} ; \mu_{\alpha}=\mu_{\beta}$
(d)$T_{\alpha}=T_{\beta} ; p_{\alpha} \neq p_{\beta} ; \mu_{\alpha} \neq \mu_{\beta}$
Answer
Answer: C ✓ checked by 4AB · confidence high
The source book printed A; on checking, C is correct — see the explanation.
Printed A; equal pressure is a condition of phase equilibrium.
Explanation
Two phases in equilibrium share thermal, mechanical and chemical equilibrium: T_α = T_β, p_α = p_β, μ_α = μ_β. The printed A (p_α ≠ p_β) is wrong for a flat interface.
Study loop for Thermodynamics