Final answer:
If ΔH < 0 and ΔS > 0, the reaction is spontaneous (ΔG < 0) in the forward direction at all temperatures, according to the Gibbs free energy equation.
Step-by-step explanation:
When ΔH is less than zero (ΔH < 0) and ΔS is greater than zero (ΔS > 0), according to the Gibbs free energy equation ΔG = ΔH - TΔS, the direction of the reaction is spontaneous at all temperatures. This is because the enthalpy change (ΔH) is negative, indicating that the reaction releases energy, and the entropy change (ΔS) is positive, meaning the disorder of the system increases.
Since the temperature (T) must always be a positive value when measured in Kelvin, the product of TΔS will also be positive. Therefore, subtracting a positive TΔS from a negative ΔH will result in ΔG being negative (ΔG < 0), which signifies a spontaneous reaction in the forward direction.