Consider the mechanism.
Step 1:
A⟶B+C slow
Step 2:
C+D⟶Efast
Overall:
A+D⟶B+E
Determine the rate law for the overall reaction, where the overall rate constant is represented ask.
r=?
To determine the rate law for the overall reaction, we need to look at the slowest step, which is Step 1. According to the given mechanism:
Step 1: A ⟶ B + C (slow)
Step 2: C + D ⟶ E (fast)
The rate law for the slow step can be determined by the stoichiometry of the reactants involved. In this case, the rate of the forward reaction in Step 1 is proportional to the concentration of A:
Rate = k1 * [A]
Since the overall reaction is a combination of Step 1 and Step 2, we need to consider the rate-determining step (Step 1) and any other reactants involved in the overall reaction. The rate law for the overall reaction can be expressed as:
Rate = k * [A] * [D]
Where k is the overall rate constant, and [A] and [D] are the concentrations of A and D, respectively.
To determine the rate law for the overall reaction, we need to consider the slowest step in the mechanism, which is Step 1 in this case. Since Step 1 is the rate-determining step, the rate of the overall reaction is determined by the rate of Step 1.
In Step 1, the reaction A ⟶ B + C is slow. To represent the rate of this step, we can use the rate law expression:
rate = k1[A]
where k1 is the rate constant for Step 1 and [A] is the concentration of reactant A.
However, we need to express the rate of the overall reaction in terms of the concentrations of A and D, as given in the overall reaction.
The overall reaction is A + D ⟶ B + E, and the stoichiometric coefficients of A and D are both 1. So, to express the rate of the overall reaction, we can use the rate law expression for Step 1 and substitute the concentrations of A and D:
rate = k1[A][D]
Thus, the rate law for the overall reaction, where the overall rate constant is represented by k, is:
rate = k[A][D]
Therefore, the rate law for the overall reaction is given by r = k[A][D].
" where the overall rate constant is represented ask.
r=?"
makes absolutely no sense to me. Please explain what this means.