For a given reaction, ΔH = 35.5 kJ mol-1 and ΔS = 83.6 J K-1 mol-1. The reaction is spontaneous at

Question

For a given reaction, $\Delta$H = 35.5 kJ mol-1 and $\Delta$S = 83.6 J K-1 mol-1. The reaction is spontaneous at (Assume that $\Delta$H and $\Delta$S do not vary with temperature.)

(a) T > 425 K

(b) all temperatures

(c) T > 298 K

(d) T < 425 K

Answer 1

Ans: (a) T > 425 K

Sol. For a spontaneous reaction,

$ΔG < 0 \text{ } i.e., ΔH - TΔS < 0$

$T> {ΔH \over ΔS}$

$T> \left({{35.5 \times1000 \over 83.6}=424.6\approx425 K}\right)$

∴ T > 425 K