JEE Main & Advanced Chemistry Thermodynamics / रासायनिक उष्मागतिकी Question Bank 2nd and 3rd law of thermodynamics and Entropy

  • question_answer
    Considering entropy (S) as a thermodynamic parameter, the criterion for the spontaneity of any process is [CBSE PMT 2004]

    A)                 \[\Delta {{S}_{system}}>0\] only

    B)                 \[\Delta {{S}_{surroundings}}>0\] only

    C)                 \[\Delta {{S}_{system}}+\Delta {{S}_{surroundings}}>0\]

    D)                 \[\Delta {{S}_{system}}-\Delta {{S}_{surroundings}}>0\]

    Correct Answer: C

    Solution :

               \[\Delta {{S}_{system}}+\Delta {{S}_{surroundings}}>O\](for spontaneity)                    Because of \[\Delta S=R\ln \frac{{{V}_{2}}}{{{V}_{1}}}\]                    Here the volume of gas increase from \[{{V}_{1}}\] to \[{{V}_{2}}\] at constant temperature T.                    The total increase in entropy of the system and its surrounding during the spontaneous process of expansion considered above is, thus\[R\,\ln \,\left( \frac{{{V}_{2}}}{{{V}_{1}}} \right)\] since \[{{V}_{2}}>{{V}_{1}}\] it is obvious that the spontaneous (irreversible) isothermal expansion of a gas is accompanied by an increase in the entropy of the system and its surrounding considered together.                                 \[\Delta {{S}_{system}}+\Delta {{S}_{surroundings}}>0\].


You need to login to perform this action.
You will be redirected in 3 sec spinner