Consider a simple model for a catalytic reaction in which a reaction 2A →B is being carried out. We assume that each catalyst particle is surrounded by a stagnant film through which A has to diffuse and reach the catalyst surface. At the catalyst surface we assume that the reaction 2A →B happens instantaneously, and that the product B then diffuses back out through the gas film to the main turbulent stream composed of A and B. What is the model for the catalytic reaction?
1) 2A →B
2) B →2A
3) A →2B
4) B →A