Final answer:
The overall reaction from the given mechanism is 2A + 2B → E + G. The rate law, governed by the slowest step, would be rate = k[D][B], and we would need additional information or assumptions to express [D] in terms of the reactants A and B.
Step-by-step explanation:
To find the overall reaction from the given mechanism, we sum up all the steps and cancel out the intermediates that appear on both the reactant and product sides. The steps are as follows:
- 2A + B → D (fast and equilibrium)
- D + B → E + F (slow)
- F → G (fast)
Cancelling out the intermediates, the overall reaction is:
2A + 2B → E + G
Next, we write the rate law (rate expression). Because the slow step dictates the rate of the overall reaction, we focus on Step 2, which gives us:
rate = k[D][B]
Since D is an intermediate formed in a fast equilibrium (Step 1), we can express its concentration in terms of A and B by applying the equilibrium expression. However, without the equilibrium constant, we cannot provide the exact expression for [D]. Therefore, under the assumption that D is in equilibrium with A and B, the rate law for our hypothetical system would depend on the concentrations of A and B:
rate = k'[A]x[B]y
However, without additional information, we can't specify the precise orders x and y in terms of A and B.