Values of Delta H and Delta S for five differ | vedclass

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Question

(D) For a reaction to be spontaneous at all temperatures,the Gibbs free energy change $\Delta G = \Delta H - T\Delta S$ must be negative at all values

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Reaction $IV$

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(D) For a reaction to be spontaneous at all temperatures,the Gibbs free energy change $\Delta G = \Delta H - T\Delta S$ must be negative at all values of $T$.This condition is satisfied when $\Delta H  0$ (increase in entropy).Looking at the given data:Reaction $I$: $\Delta H > 0, \Delta S > 0$ (Spontaneous at high $T$)Reaction $II$: $\Delta H Reaction $III$: $\Delta H > 0, \Delta S Reaction $IV$: $\Delta H  0$ (Spontaneous at all $T$)Reaction $V$: $\Delta H > 0, \Delta S = 0$ (Non-spontaneous at all $T$)Therefore,Reaction $IV$ is spontaneous at all temperatures.

Substance	$\Delta H^{\circ} \text{ (kJ mol}^{-1})$	$\Delta S^{\circ} \text{ (J mol}^{-1} \text{ K}^{-1})$
$FeO_{(s)}$	$-266.3$	$57.49$
$C_{(\text{graphite})}$	$0$	$5.74$
$Fe_{(s)}$	$0$	$27.28$
$CO_{(g)}$	$-110.5$	$197.6$

Similar Questions

For an irreversible process occurring at constant $T$ and $P$,where only pressure-volume work is involved,which condition for entropy change $(\Delta S)$ and Gibbs free energy change $(\Delta G)$ is satisfied?

What happens during a spontaneous process?

Which of the following pairs of a chemical reaction is certain to result in a spontaneous reaction?

If $\Delta H > 0$ and $\Delta S > 0$,the reaction can proceed spontaneously at:

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Reaction	$\Delta H \ (kJ \ mol^{-1}) / \Delta S \ (J \ K^{-1} \ mol^{-1})$
$I$	$+98.0, +14.8$
$II$	$-55.5, -84.6$
$III$	$+28.3, -17.0$
$IV$	$-40.5, +24.6$
$V$	$+34.7, 0.0$