5.Kinetics

Question 1

What is collision theory

Answer 1

Reactions can only occur when collisions take place between particles with sufficient energy (activation energy)

Question 2

Name all the factors that affect the rate of reaction

Answer 2

• temperature
• concentration of a solution
• pressure of a gas reaction
• surface area of solid reactants
• using a catalyst

Question 3

What is activation energy

Answer 3

The minimum energy that a particle needs in order to react or the enthalpy change between the reactants and the transition state

Question 4

What is the transition state

Answer 4

The species that exists at the top of the curve of an enthalpy diagram

Question 5

What does the Maxwell-Boltzmann distribution show

Answer 5

The distribution of energy amongst the particles. It shows:

• no particles have zero energy
• most particles have intermediate energies
• a few have very high energies (there is no upper limit)

Question 6

Why does the Maxwell-Boltzmann distribution go through the origin

Answer 6

All particles have energy/ no particles have no energy

Question 7

Why does the Maxwell-Boltzmann distribution never touch the x-axis after it goes through the origin

Answer 7

There is always a probability that a particle has any energy even a very high one

Question 8

Describe the effect of temperature on a Maxwell-Boltzmann curve

Answer 8

• curve shifts to the right
• number of particles with very high energy increases
• total area under the curve remains the same
• number of particles with Ea increases

Question 9

What are catalysts

Answer 9

A catalyst is a substance that increases the rate of a chemical reaction without being changed in chemical composition or amount

Question 10

How do catalysts work

Answer 10

They provide a different reaction pathway with a lower activation energy

Question 11

Describe the effect of a catalyst on a Maxwell-Boltzmann curve

Answer 11

It moves the position of the Ea down the x-axis on the graph

Question 12

Describe a catalytic converter

Answer 12

a honeycomb, made of a ceramic material, coated with platinum and rhodium metals (the catalysts). honeycomb to increase surface area.

Question 13

Describe 2 catalytic converters reactions

Answer 13

carbon monoxide +nitrogen oxides——> nitrogen and carbon dioxide

hydrocarbons + nitrogen oxides——> nitrogen +carbon dioxide + water

Question 14

Describe the steps of the reaction that take place on the catalytic converter

Answer 14

1. adsorption - gases form weak bonds with metals atoms of the catalyst. The gases react on the surface.
2. desorption- the products break away from the metal atoms.