MCQ
For a reaction, $\Delta H = -40\,kJ$ and $\Delta S = -50\,J/K$ . At what temperature range will it change from spontaneous to non-spontaneous ?
- A$0.8\, K$ to $1\,K$
- B$799 \,K$ to $800 \,K$
- C$800\, K$ to $801 \,K$
- ✓$799 \,K $ to $801 \,K$
✓
Answer
Correct option: D.
$799 \,K $ to $801 \,K$
d
$T = \frac{{\Delta H}}{{\Delta S}} = 800\,K$ (equilibrium)
$T = \frac{{\Delta H}}{{\Delta S}} = 800\,K$ (equilibrium)
$\Delta G = \Delta H - T\Delta S$
below $800\, K$ spontaneous
above $800 \,K$ non-spontaneous
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