Question

The correct thermodynamic conditions for the spontaneous reaction at all temperatures is

• A. $\Delta H<0and\Delta S>0$
• B. $\Delta H<0and\Delta S<0$
• C. $\Delta H<0and\Delta S=0$
• D. $\Delta H>0and\Delta S<0$

Answer 1

Answer: (A), (C)

$\Delta H<0and\Delta S=0$

$\Delta G=\Delta H-T\Delta S$
$If\Delta H<0and\Delta S>0$
$\Delta G=(-ve)-T(+ve)$
Then at all temperatures, $\Delta G=-ve$, spontaneous reaction.
If $\Delta H<0and\Delta S=0$
$\Delta G=(-ve)-T\left(0\right)=-ve$ at all temperatures.