H and S for a reaction are 35.5 kJ mol ⁻¹ and 83.6 J K ⁻¹ respectively. Assuming that H and S do not vary with temperature, the reaction is spontaneous when:

Step-by-step solution

For a reaction to be spontaneous, the change in Gibbs free energy must be negative, G Using the Gibbs free energy equation: G = H - T S For spontaneity: H - T S T > H S Given values are: H = 35.5 kJ mol ⁻¹ = 35500 J mol ⁻¹ S = 83.6 J K ⁻¹ mol ⁻¹ Substituting the values: T > 35500 83.6 T > 424.64 K Therefore, the reaction is spontaneous when T > 425 K . Answer: T > 425 K