The effect of temperature on the spontaneity | vedclass

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(A) The spontaneity of a reaction is determined by the Gibbs free energy equation: $\Delta G = \Delta H - T \Delta S$. For a reaction to be spontaneou

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$A, B, C$ and $D$

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(A) The spontaneity of a reaction is determined by the Gibbs free energy equation: $\Delta G = \Delta H - T \Delta S$. For a reaction to be spontaneous, $\Delta G $1$. If $\Delta H > 0$ and $\Delta S  0$ and $T \Delta S > 0$, $\Delta G$ is always positive. Thus, the reaction is non-spontaneous at all temperatures. ($A$ is correct).$2$. If $\Delta H > 0$ and $\Delta S > 0$, then $\Delta G = \Delta H - T \Delta S$. $\Delta G  \Delta H$, i.e., at high temperatures. At low temperatures, $\Delta G > 0$ (non-spontaneous). Thus, $B$ is correct.$3$. If $\Delta H  |T \Delta S|$, i.e., at low temperatures. Thus, $C$ is correct.$4$. If $\Delta H  0$, then $\Delta G = -\Delta H - T(\Delta S)$. Since both terms are negative, $\Delta G$ is always negative. Thus, the reaction is spontaneous at all temperatures. ($D$ is correct).All conditions $A, B, C,$ and $D$ are correctly matched.

Condition	Details
$A$. $\Delta H: +, \Delta S: -$	$T$: any $T$, Spontaneity: Non-spontaneous
$B$. $\Delta H: +, \Delta S: +$	$T$: low $T$, Spontaneity: Non-spontaneous
$C$. $\Delta H: -, \Delta S: -$	$T$: low $T$, Spontaneity: Spontaneous
$D$. $\Delta H: -, \Delta S: +$	$T$: any $T$, Spontaneity: Spontaneous

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