Kinetics

Question 1

What is the definition of a rate of reaction?

Answer 1

The change in concentration of a reactant or a product over time

Question 2

What are the factors which may affect the rate of a chemical reaction?

Answer 2

Temperature
Concentration
Pressure
Surface area (of solids)
Catalyst

Question 3

What 2 things need to happen for a chemical reaction to occur according to collision theory?

Answer 3

Particles must collide in the correct orientation
Particles must collide with sufficient energy (the activation energy)

Question 4

The effect of concentration on aqueous solutions?

Answer 4

The concentration affects the rate of reaction
At a higher concentration there are more reactant particles in a given volume
There are more frequent collisions and therefore more successful collisions per unit time- the reaction rate increases

Question 5

The effect of increasing gas pressure on rate of reaction?

Answer 5

When the pressure of a gas increases- the volume of the container decreases- the molecules are pushed closer together
The number of molecules remains the same but the space occupied is less
There are more frequent collisions and therefore more successful collisions
Increased ROR

Question 6

How can the rate of reaction be calculated?

Answer 6

By recording the amount of a reactant or a product at regular time intervals during a single reaction or by determining the initial rate of several reactions and finding an average

Question 7

What are the methods of continuous monitoring?

Answer 7

Monitoring by gas collection- use a syringe to measure the volume of gas evolved
Mass loss- set up the system on a balance so the decrease in mass of reactants can be measured
Colorimetry- concentration change is monitored by measuring the amount of light absorbed by a sample

Question 8

What do clock reactions and initial rate calculations allow for?

Answer 8

Allow determination of the rate of reaction for a specific concentration

Question 9

What are some easy observable endpoints to show the time taken for a certain amount of products to form?

Answer 9

A colour change- e.g. iodine clock reactions causes an orange to dark blue colour change
A precipitate formation from a clear solution

Question 10

What does the mean rate of reaction tell you?

Answer 10

The average rate for the reaction up to a certain amount of time