Thermodynamics and Thermochemistry 1 Question 24

27. For the process $\mathrm{H}{2} \mathrm{O}(l)(1 \mathrm{bar}, 373 \mathrm{~K}) \rightarrow \mathrm{H}{2} \mathrm{O}(g)$ (1 bar, $373 \mathrm{~K}$ ), the correct set of thermodynamic parameters is

(2007, 3M)

(a) $\Delta G=0, \Delta S=+$ ve

(b) $\Delta G=0, \Delta S=-$ ve

(c) $\Delta G=+$ ve, $\Delta S=0$

(d) $\Delta G=-$ ve, $\Delta S=+$ ve

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Solution:

  1. At transition point ( $373 \mathrm{~K}, 1.0$ bar), liquid remains in equilibrium with vapour phase, therefore $\Delta G=0$. As vaporisation occur, degree of randomness increases, hence $\Delta S>0$.