(A) For a spontaneous reaction,the Gibbs free energy change $ \Delta G $ must be negative,where $ \Delta G = \Delta H - T \Delta S $.If $ \Delta H $ i

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$ \Delta H $ value is positive and $ \Delta S $ value is negative

(A) For a spontaneous reaction,the Gibbs free energy change $ \Delta G $ must be negative,where $ \Delta G = \Delta H - T \Delta S $.If $ \Delta H $ is positive and $ \Delta S $ is negative,then $ \Delta G = (+ \Delta H) - T(- \Delta S) = + \Delta H + T \Delta S $.Since both terms are positive,$ \Delta G $ will always be positive regardless of the temperature $ T $.Therefore,the reaction cannot occur spontaneously under any conditions.

Class 11 Chemistry Thermodynamics Free energy and Work

Easy

$A$ chemical reaction cannot occur at all if

A
$ \Delta H $ value is positive and $ \Delta S $ value is negative
B
$ \Delta H $ value is negative and $ \Delta S $ value is positive
C
$ \Delta H $ and $ \Delta S $ values are negative but $ \Delta H > T \Delta S $
D
$ \Delta H $ and $ \Delta S $ values are positive but $ \Delta H > T \Delta S $