Kinetic_ans

Kinetic_ans - Revised Spring, 2000 Kinetics Supplementary...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
Revised Spring, 2000 Kinetics Supplementary Sheet 1. From the following reaction mechanism determine the overall chemical equation and the rate law. 2B ----> B 2 (fast) A + B 2 ------> AB 2 (slow) AB 2 -------> B + C (fast) The overall equation for this reaction is simply the sum of the individual steps in the reaction. In this case the equations add up to the equation A + B -------> C . The rate law is derived from the slow step in the mechanism, for this reaction the rate law is rate = k[A][B 2 ]. However, rate laws are usually given in terms of the reactants not an intermediate. Since the first step of the reaction involves the formation of B 2 from 2B in a fast step, the [B 2 ] is proportional the [B] 2 . The rate law then becomes rate = k[A][B] 2 . 2. For the reaction A + B 2 -----> AB + B, which is catalyzed by C, the rate law is rate = k[B 2 ][C]. Suggest a mechanism, indicating the slow step, for this reaction that agrees with this rate law. Since B 2 and C are involved in the mechanism, they must combine in the slow step to form some type of intermediate, such as B 2 C. This intermediate then combines with A in a fast step to produce the products AB and B along with the catalyst C. This shows how C can be neither a reactant nor a product yet still be present in the rate law. B 2 + C -------> B 2 C (slow) B 2 C + A -------> AB + B + C (fast) B 2 + A -------> AB + B (desired overall equation) Note: Other mechanisms are also possible, all involve the reaction of C in or before the slow step and the reformation of C later as a product.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
3. The following kinetic data were obtained for the reaction: 3A + 2B -------> 2C + D. Based on the above data determine the following:
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 5

Kinetic_ans - Revised Spring, 2000 Kinetics Supplementary...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online