1. Example: The decay of 1,2-dichloropropene in soil. DaysAmount % 0100 1050 2025 3012.5 406.25 503.125 601.5625 Use excel Plot scatter graphs

2. 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

3. Data in spreadsheet Number of half-livesDaysAmount % 00100 11050 22025 33012.5 4406.25 5503.125 6601.5625

4. Adding a scatter graph Highlight days and amount cells Click insert and select ‘Scatter’ Select the icon circled

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

6. Changing axis

7. Adding gridlines Right mouse click on y-axis and select minor gridlines Repeat for x-axis but select both major and minor gridlines

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

9. Adding titles Click layout Select ‘axis titles’ Select primary vertical axis title Select rotated title and add axis title Repeat for primary horizontal title

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