KEAM 2014 Physics and Chemistry Paper

Given entropy of vaporisation =58JK−1mol−1 i.e., entropy change when 1 mole of the liquid vapourises =58JK−1
∴ Entropy change when 1 mole of the liquid condense =−58JK−1
( ∵ Condensation and vaporisation are opposite process).
Moles of the liquid used in the reaction
=‌

100

58

=1.72mol
∴ Entropy change when 1.72 mole for 100g ) of the liquid condenses
=‌

−58×1.72

1

=−100JK−1