The basis for spontaneous reactions and their dependence on temperature is given by the equation for the Gibbs Free energy:
ΔG = ΔH – TΔS < 0
For a spontaneous reaction to occur, ΔG must be negative. Following the equation, ΔH must be < 0, and ΔS must be > 0 for a reaction to be spontaneous at all temperatures. However, the given values have a negative value for both enthalpy and entropy. This means that spontaneity can only occur below a certain temperature, which can be calculate by setting ΔG as zero. This gives:
ΔG = ΔH – TΔS = 0
T = ΔH/ΔS = -50/-0.3 = 166.67 Kelvin
Anything below that temperature gives a negative ΔG, making it spontaneous.
