Consider the following catalytic reaction mechanism. Gas reactants A \& B adsorb to a catalyst surface by molecular adsorption. These two adsorbed species on the surface participate in a dual site surface reaction that is nonreversible. The products are C and D, which are gas products that are never adsorbed on the surface. Step 1 adsorption: A+SAS Step 2 adsorption: B+SBS Step 3 surface reaction: AS+BSC(g)+D(g)+2S Derive the catalytic rate expression from the reaction mechanism assuming that the surface reaction is the rate limiting step