Considering entropy (S) as a thermodynamic parameter, the criterion for the spontaneity of any process is

Options

(a) ΔS system + ΔS surroundings > 0
(b) ΔS system – ΔS surroundings > 0
(c) ΔS system > 0 only
(d) ΔS surroundings > 0 only

Correct Answer:

ΔS system + ΔS surroundings > 0

Explanation:

ΔS = Rln V₂/V₁,
Here the volume of gas increases from V₁ to V₂ at consant temperature T. The total increase in entropy of the system and its surroundings during the spontaneous process of expansion considered above is, thus R ln (V₂/V₁).Since V₂ > V₁, it is obvious that the spontaneous (irreversible) isothermal expansion of a gas is accompanied by a increase in the entropy of the system and its surroundings considered together.
ΔS(sys) + ΔS(surr > 0.