Question

For a particular reaction, DHŗ = – 40 kJ and DSŗ = – 200 J K^–1mol^–1. The reaction is

• A. Spontaneous at all temperatures
• B. Non-spontaneous at all temperatures
• C. Spontaneous at temperature below – 73ŗ C
• D. Spontaneous at temperature above – 73ŗ C

Answer 1

Answer: (D)

Spontaneous at temperature above – 73ŗ C

Answer 2

DG⁰ = DH⁰ – TDS⁰

When DG⁰ = 0, T = $\frac{\Delta Hº}{\Delta Sº}$ = $\frac{- 40 \times 10^{3}}{- 200}$= 200 K