10.1 - Reaction rates

Question 1

What is meant by rate of reaction?

Answer 1

The rate of a reaction measures how fast a reactant is being used up or how fast a product is being formed.

Question 2

What is the equation for rate of reaction?

Answer 2

rate = change in conc / time

Question 3

When is the rate of reaction fastest?

Answer 3

At the start of a reaction as each reactant is at its highest concentration.

Question 4

What happens when all reactants are used up?

Answer 4

Concentration stops changing and rate of reaction is zero.

Question 5

What is the collision theory?

Answer 5

Collision theory states that two reacting particles must collide for a reaction to occur.

Question 6

When will a collision be effective?

Answer 6

If the particles collide with the correct orientation.
If the particles have sufficient energy to overcome the activation energy barrier of the reaction.

Question 7

How does increasing the concentration affect the rate of reaction?

Answer 7

The more concentrated a solution is, the greater the number of particles in a given volume of solvent
An increase in concentration causes in an increased collision frequency and therefore an increased rate of reaction

Question 8

How does increasing the pressure affect the rate of reaction?

Answer 8

An increase in pressure in reactions that involve gases has the same effect as an increase in the concentrations of solutions
When the pressure is increased, the molecules have less space in which they can move
This means that the number of effective collisions increases due to an increased collision frequency

Question 9

If a reaction produces gas, how can you determine the rate of reaction?

Answer 9

• Monitoring the volume of gas produced at a regular time interval using gas collection in a gas syringe
• Monitoring the loss of mass of reactants using a balance