Example: The decay of 1,2-dichloropropene in soil.

Days Amount %0 100

10 5020 2530 12.540 6.2550 3.12560 1.5625

Use excel

Plot scatter graphs

Decay of 1,2-dichloropropene

• Half life is 10 days• Plot a scatter graph to show the decay of 1,2-

dichloropropene in the environment over 6 half-lives starting with 100% at day 0

Data in spreadsheet

Number of half-lives Days Amount %

0 0 100

1 10 50

2 20 25

3 30 12.5

4 40 6.25

5 50 3.125

6 60 1.5625

Adding a scatter graph

Highlight days and amount cellsClick insert and select ‘Scatter’Select the icon circled

Changing axis

Right mouse click on y axis and select ‘format axis’.Click fixed and enter data

Changing axis

Adding gridlines

Right mouse click on y-axis and select minor gridlinesRepeat for x-axis but select both major and minor gridlines

Adding a trend line

Right mouse click on a data point, select ‘add trend line’ and select exponential

Adding titles

Click layoutSelect ‘axis titles’Select primary vertical axis titleSelect rotated title and add axis titleRepeat for primary horizontal title

0 10 20 30 40 50 600

10

20

30

40

50

60

70

80

90

100

Decay of 1,3-dichoropropene

Time (days)

Am

ount

(%)

0 10 20 30 40 50 600

10

20

30

40

50

60

70

80

90

100

Decay of 1,3-dichloropropene

Time (days)

Am

ount

(%)

How long does it take for concentration to fall to 10% / 5% of the original value?