Question

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

• A. $\Delta S_{system}+\Delta S_{surrounding}>0$
• B. $\Delta S_{system}-\Delta S_{surrounding}>0$
• C. $\Delta S_{system}=0$
• D. $\Delta S_{surrounding}=0$

Answer 1

Answer: (A)

$\Delta S_{system}+\Delta S_{surrounding}>0$

Entropy (S) is the measure of randomness or disorder of the molecules. It is an extensive property and a state function.

A process is spontaneous if and only if the entropy of the universe increases.

Therefore, for the spontaneous process,

$\Delta S_{total}>0$

${\Delta S}_{total}={\Delta S}_{system}+{\Delta S}_{surrounding}$

$\therefore \Delta S_{system}+\Delta S_{surrounding}>0.$