A reaction is not feasible or non-spontaneous, if enthalpy (ΔH) is positive and entropy change (ΔS) is negative because ΔG (Gibb's free energy change) will be positive. The changes in Gibb's free energy is given as ΔG=ΔH−TΔS=(+ve)−T(−ve) ΔG=+ve Hence, ΔG will be positive for non - spontaneous reaction.