Consider the following sequence of elementary steps occurring in aqueous solution at 298 K.
Step 1 A + B ⇌ C (fast)
Step 2 C + B ⇌ D (fast)
Step 3 D → E + F (slow)
No other steps occur, and all species remain in solution. The overall stoichiometry is A + 2 B → E + F.
(a) Derive an expression for the initial rate in terms of the concentrations of the reactants A and B and the rate constant kslow for Step 3, eliminating all intermediates.
(b) Write the composite equilibrium constant Koverall in terms of the stepwise equilibrium constants K1 and K2. Then express the rate law from part (a) using Koverall instead of K1 and K2.
(c) Identify the overall reaction order implied by your derived rate law and explain how this order would be verified experimentally.