FINAL - Chapter 9 Kinetics

Question 1

What is the red flag of kinetics?

Answer 1

A single termolecular step is super rate

Three reactants in rate law

Question 2

Outline pre-equilibrium assumption and what it works for?

Answer 2

First step fast and has k1 and k-1 and second step slow

Write the rate expressions for rate 1 and rate -1

Relative to slow step, fwd/rev rxn for fast step have approx same rate so set equal and isolate for variable in rate expression of slow step

Sub in

Question 3

Outline steady state approximate

Answer 3

Pretty much works for anything but harder so attempt pre -equilibrium first

Assumes: rate of production of intermediate = rate of consumption of intermediate

Write out the equations for rate of production of intermedaite (wherever it is product) and rate of consumption

Set equal and isolate for intermediate

Subsitute into the rate equation

Recall that k-1>k2
Test if concentration in denominator is very high and if very low, and if different rate law, shows that it does occur in two steps

Question 4

What is a trick with the finding the correct rate law?

Answer 4

If the intermediate doesn’t cancel out to create overall reaction, then automatically proposed mechanism fails