Question

Consider the following elementary steps that make up the mechanism of a certain reaction: 3X→E+F E+M→F+N

Answer 1

Answer:

Part A- The overall reaction is: 3X + M → 2 F + N.

Part B- The intermediate of this reaction is E.

Part C- Rate law for step 1 = k[X]³ = k*[X]^3.

Part D- Rate law for step 2 = k[E][M] = k*[E]*[M].

Explanation:

Part A: What is the overall reaction? Express your answer as a chemical equation.

• We can get the overall reaction by summing the two steps of the reaction.

Step 1: 3X → E + F.

Step 2: E + M → F + N.

The E component in the products side in step 1 will cancel that in the reactants side of step 2.

∴ The overall reaction is: 3X + M → 2 F + N.

Part B: Which species is a reaction intermediate?

• We should identify the intermediate firstly to determine the reaction intermediate.

The intermediate is the species that produced in a step of the reaction and consumed in next steps and do not appear in the overall reaction

So, the intermediate of this reaction is E.

Part C: What is the rate law for step 1 of this reaction?

The rate of the reaction is directly proportional to the concentration of the reactants.

Rate = k[reactants]ˣ.

where, k is the rate constant of the reaction,

x is the no. of moles of the reactants that involved in the reaction mechanism before the rate determining step.

So, The rate law for step 1 of this reaction (neglecting the mechanism) is:

Rate = k[X]³ = k*[X]^3.

Part D: What is the rate law for step 2 of this reaction?

Also, as in part C:

The rate law for step 2 of this reaction (neglecting the mechanism) is:

Rate = k[E][M] = k*[E]*[M].