Given :
ΔH0 = – 224 kJ = – 224000 J
ΔS0 = – 153 JK-1
Temperature (T) at which, reaction changes from spontaneous to non-spontaneous = ?
Find the temperature at equilibrium, where ΔG0 = 0
ΔG0 = ΔH0 - TΔS0
0 = ΔH0 – TΔS0
∴ TΔS0 = ΔH0
∴ T = \(\frac{ ΔH^0}{ ΔS^0}\)
= \(\frac{224000}{153}\)
= 1464 K.
Hence reaction will be spontaneous below 1464 K. It will be at equilibrium at 1464 K and non-spontaneous above 1464 K.
∴ Change over temperature from spontaneous to non-spontaneous = 1464 K.