If ΔH = - 50.0 kJ and ΔS = - 0.300 kJ/K, the reaction is spontaneous below a certain temperature. Calculate that temperature.

The basis for spontaneous reactions and their dependence on temperature is given by the equation for the Gibbs Free energy:

ΔG = Δ H - TΔ S < 0

For a spontaneous reaction to occur, ΔG must be negative. Following the equation, ΔH 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.