4. The gas-phase solid-catalyzed reaction A+BC 1 occurs as per the expression r=(1+CA+CC)kCACB,=1L/mol,=4L/mol The reactor feed contains 30%A,60%B and 10% inerts, with CA0 being 4mol/L. It is desired to convert 90% of A in a packed bed (plug flow) reactor. (a). Calculate the catalyst mass (i.e., the value of kW/vo ) required to achieve this conversion. (b). Propose a reaction mechanism that is consistent with the rate expression and identify the rate limiting step