Paper: CSIR-NET December 2012 · Subject: Physical Chemistry · Chapter: Thermodynamics · Topic: Thermodynamics – General · Marks: 2 · Difficulty: Medium
The fugacity of a gas depends on pressure and the compressibility factor $\mathrm{Z}(=\mathrm{p} \tilde{\mathrm{V}} / \mathrm{RT})$ through the relation ( $\tilde{\mathrm{V}}$ is the molar volume). For most gases at temperature T and up to moderate pressure, this equation shows that
(a)$\mathrm{f}<\mathrm{p}$, if T $\rightarrow 0$
(b)$\mathrm{f}<\mathrm{p}$, if T $\rightarrow \infty$
(c)$\mathrm{f}>\mathrm{p}$, if $\mathrm{T} \rightarrow 0$
(d)$\mathrm{f}=\mathrm{p}$, if T $\rightarrow 0$
Answer
Answer: A ✓ checked by 4AB · confidence high
Explanation
At low temperature attractions dominate, Z < 1 and ln(f/p) = ∫(Z − 1)dp/p < 0: f < p.