3.2 Controlling the rate

Question 1

collision theory

Answer 1

Reaction rates must be controlled in industrial processes. If the rate is too low then the process will not be economically viable, if it is too high there will be a risk of explosion.

Question 2

what effects on reaction rates can be explained with the collision theory?

Answer 2

 concentration
 pressure
 surface area (particle size)
 temperature
 collision geometry

Question 3

enthalpy change

Answer 3

The enthalpy change is the energy difference between the products and the reactants. The enthalpy change has a negative value for exothermic reactions or a positive value for endothermic reactions.

Question 4

activation energy

Answer 4

The activation energy is the minimum energy required by colliding particles to form an activated complex and can be calculated from potential energy diagrams

Question 5

activated complex

Answer 5

The activated complex is an unstable arrangement of atoms formed at the maximum of the potential energy barrier, during a reaction.

Question 6

effect of catalyst on reaction pathway

Answer 6

A catalyst provides an alternative reaction pathway with a lower activation energy.

Question 7

Temperature

Answer 7

Temperature is a measure of the average kinetic energy of the particles in a substance.

Question 8

Activation energy

Answer 8

The minimum kinetic energy required by colliding particles before a reaction may occur

Question 9

How can you explain the effects of temperature and adding a catalyst?

Answer 9

In terms of a change in the number of particles with energy greater than the activation energy