Question

2

Rate =

Consider the overall reaction: AB(g) + CB(g) ⟶ A(g) + CB2(g)

A proposed mechanism for this reaction is

2 AB(g) ⇌  AB2(g) + A(g) (fast)

AB2(g) + CB(g) ⟶ AB(g) + CB2(g) (slow)

Based on this mechanism, determine the rate law for the overall reaction.

Express your answer in terms of k and the necessary concentrations (ex: k[X][Y]^2). Use brackets around the concentrations and the caret symbol prior to the exponent. Do not include any multiplication signs. Type in subscripts as normal numbers (ex: AB2, CB2).

Rate =

Answer 1

Rate depends on the slowest step

Here 2nd step is slowest

So, rate law is:

rate = k2[AB2][CB]

Here AB2 is intermediate.

So, we need to remove it.

From step 1:

Kc = [AB2][A]/[AB]^2

[AB2] = Kc[AB]^2[A]^-1

put this in rate law expression:

rate = k2[AB2][CB]

rate = k2Kc[AB]^2[A]^-1[CB]

Let k2Kc be k

so,

rate = k[AB]^2[A]^-1[CB]

Answer: rate = k[AB]^2[A]^-1[CB]