1. Making a Scatterplot

2. Open Excel document
Set it up like the image on the right

3. Enter your data in both roles in the table
Make sure YOUR DATA is in the “% change in mass” line

4. Highlight all of your data by dragging over the top

5. Click “insert” on the top ribbon
Select the scatterplot option

6. On the menu that drops down, select the dots with no line option

7. It will create a graph that looks like this

8. On the graph, right click on one of the dots, and this menu should come up

9. Select “Add Trendline” from the options

10. Once you click “Add trendline”, this menu should pop up
Check the box next to “Display Equation on Chart”

11. The Equation will pop up on your graph

12. We want the concentration of an isotonic solution
An isotonic solution has no change in mass, so we will set y = 0
We want to know exactly where our line crosses the x axis

13. Then you just do some algebra
My equation was y = x
Set y = 0 and solve for x
0 = x (subtract from each side)
= x (divide each side by )
.18 = x
So this means .17m is my concentration of an isotonic solution
I would plug in .17 for C in the –iCRT equation

14. Save your work somewhere you will be able to find it later, and continue by starting your lab report