The effect of temperature on the selectivity of a reaction with regards to Product A and Product B when using a specific catalyst can be explained by considering the reaction kinetics and thermodynamics.1. Reaction kinetics: The rate of a chemical reaction is influenced by temperature. According to the Arrhenius equation, the reaction rate constant k is related to temperature T as follows:k = Ae^-Ea/RT where A is the pre-exponential factor, Ea is the activation energy, R is the gas constant, and T is the temperature in Kelvin. As the temperature increases, the reaction rate constant increases, leading to a faster reaction rate.Different reactions have different activation energies Ea . If the formation of Product A has a lower activation energy than the formation of Product B, then increasing the temperature will favor the formation of Product A more than Product B, leading to higher selectivity towards Product A. Conversely, if the formation of Product B has a lower activation energy, then increasing the temperature will favor the formation of Product B more than Product A, leading to higher selectivity towards Product B.2. Reaction thermodynamics: The equilibrium constant K of a reaction is related to the Gibbs free energy change G and temperature as follows:G = -RT ln K where R is the gas constant, T is the temperature in Kelvin, and K is the equilibrium constant. The Gibbs free energy change is also related to the enthalpy change H and entropy change S of the reaction:G = H - TSAs the temperature increases, the entropy term TS becomes more significant. If the formation of Product A has a more positive entropy change S than the formation of Product B, then increasing the temperature will favor the formation of Product A more than Product B, leading to higher selectivity towards Product A. Conversely, if the formation of Product B has a more positive entropy change, then increasing the temperature will favor the formation of Product B more than Product A, leading to higher selectivity towards Product B.In summary, the effect of temperature on the selectivity of a reaction with regards to Product A and Product B when using a specific catalyst depends on the activation energies and thermodynamic properties of the reactions involved. By understanding these factors, chemists can optimize reaction conditions to achieve the desired selectivity.