Topic 16.1 - Rate expression and reaction mechanism

Question 1

Rate expression

Answer 1

Rate = rate constant(k) x [RDS]ⁿ

Question 2

Molecularity and RDS

Answer 2

RDS can either be unimolecular, bimolecular, or trimolecular

Question 3

Units of rate constant

Answer 3

k = rate expression/[RDS]ⁿ

Working out units = rate units (mol dm⁻³ s⁻¹/m⁻¹) / units of [RDS]

Make sure to account for any parts of the RDS that are squared. Easiest way to work it out, make the equation

Question 4

Graph for the rate expression with temperature

Answer 4

Graph consists of 1/T and lnK.

x-axis: 1/T
y-axis: lnk

Question 5

Easier method to rate constant

Answer 5

First order: S⁻¹
Second order: mol⁻¹ dm³ S⁻¹
Third order: mol⁻² dm⁶ S⁻¹