P2: 18 Kinetics

Question 1

What is the Arhennius equation?

Answer 1

k = Ae ^ -Ea/RT

k - rate constant
Ea - activation enery (J)
T - temperature (K)
R - gas constant
A - Arrhenius constant

Question 2

Define ‘order of reaction’.

Answer 2

The power to which the concentration of its reactant is raised in the rate equation.

Question 3

Define ‘rate constant’.

Answer 3

k, a number that links the rate of reaction to the concentration of the reactants.

Question 4

What effect does increasing the temperature have on the rate constant, k?

Answer 4

Increasing temperature increases the rate of reaction. But the concentrations and orders of the reaction stay the same. So k must increase for the rate equation to balance.

Question 5

What’s the rearrangement of the Arrhenius equation to give lnk?

Answer 5

lnk = lnA - Ea/RT

Question 6

On an Arrhenius plot (graph), what are the x and y axes?

Answer 6

x - 1/T
y - lnk

Question 7

On an Arrhenius plot (graph), what does the gradient represent?

Answer 7

-Ea/R

Question 8

What is the rate equation determined by?

Answer 8

Experiment.

Question 9

What can the orders with respect to reactants provide information about?

Answer 9

The mechanism of a reaction.

Question 10

How do you work out the rate determining step?

Answer 10

The reactants appear in the rate equation.
The order of a reaction with respect to a reactant shows the number of molecules of that reactant that are involved in the rate determining step.