For a particular reaction, Δ H ∘ = − 46.7 kJ and Δ S ∘ = − 123.8 J/K. Assuming these values change very little with temperature, at what temperature does the reaction change from nonspontaneous to spontaneous?

377 K

Explanation:

According to Gibbs equation

= Gibbs free energy  

= enthalpy change = -46.7 kJ=   -46700 J

= entropy change  = -123.8 J/K

T = temperature in Kelvin  = ?

= +ve, reaction is non spontaneous

= -ve, reaction is spontaneous

= 0, reaction is in equilibrium

Thus at 377 K the reaction change from nonspontaneous to spontaneous

the answer is 303.15 or 303