Half Life

Question 1

Half life is?

Answer 1

The time taken for half of a reactant (in concentration) to be used up

Question 2

What graph do we use to find the half life?

Answer 2

Using a concentration time graph

Question 3

How to find the half life on a concentration time graph

Answer 3

Choose 2 concentrations on the y axis: one at half of the other eg 8 and 4
Interpolate from the graph to find the time at each concentration
This time difference (time taken for concentration to halve) will be the half life

Question 4

Half life of a 1 order concentration-Time graph

Answer 4

Half life will be the same no matter the concentration
Because the concentration is proportional to the time (because it’s proportional to rate of reaction)

Question 5

Half life of a 1 order reaction

Answer 5

Independent of changing the concentration of a 1 order reactant

Question 6

Why is half life useful?

Answer 6

Cos then we can identify a 1 order reactant with a concentration time graph without having to draw a rate concentration graph for it

Question 7

Using half life to find rate orders

Answer 7

Using continuous rate data to find half life of to find order of a particular reactant without having to draw rate-conc graphs

Question 8

Continuous rate data

Answer 8

Data where conc of one reactant is monitored throughout experiment and the other reactants are at excess so do not change to have an effect on the rate of reaction