1. CO2 Diffusion Through Gelatin Experiment
Presented by
Jennifer Welborn June 2012

2. Learning Goals..
Through this PowerPoint, STEMDIGITAL participants will:
See how the concept of diffusion is related to a variety of curricular standards
Understand how ADI software can be used to show the process and rate of diffusion both qualitatively and quantitatively

3. OVERVIEW Multidiscipline Standards Alignment Concept Development
Factors Affecting Rate of Diffusion
Diffusion and Global Environmental Change
Research Questions
Experiment--Diffusion of CO2 Through Gelatin: Model of Diffusion in Cells
Using the Digital Camera as a Data Collection Tool
Analyzing Data Using ADI Software

4. Standards Alignment
Physical Science/Chemistry: particle motion theory; pH; temperature; mixtures and solutions; color change as an indicator of a change in physical properties/chemical composition; acid/base indicators and protonation
Biology: passive transport; cellular structure, etc.
Ecology/Environmental Science: environmental effects on living cells/systems
Math: rates; relationships; data collection, organization, analysis, interpretation, ratios and proportions

5. Diffusion
Diffusion– movement of a substance from a region of higher concentration to a region of lower concentration.
Diffusion continues until equilibrium--- the concentration of a substance is equal throughout a space

6. Carbon dioxide from the environment diffuses into plant cells
Diffusion and Cells
Dissolved particles that are small or non-polar can diffuse through the
cell membranes.
The process of diffusion is one of the ways in which substances like oxygen, carbon dioxide and water move into and out of cells.
Carbon dioxide from the environment diffuses into plant cells

7. Factors That Affect Rate of Diffusion
Temperature
Concentration of material diffusing
Density of substance material is diffusing into
Particle Size
Diffusion and Global Environmental Change
What might be the impact of increasing temperatures and
atmospheric CO2 levels on diffusion in cells?

8. Research Questions
Can a digital camera be used to quantify a change in the
color of gelatin with BTB in it as carbon dioxide
diffuses through it over time?
What affect might an increase in the concentration of CO2
have on the rate of CO2 diffusion through the gelatin?
What effect might an increase in temperature have on the
rate of diffusion?
How might this model apply to living organisms and changes
in the environment?

9. Conducting the Experiment/Gathering and Analyzing Data
Set up the experiment according to the directions on the lab directions handout.
Photograph the control at the beginning, then a sample of each cube exposed to CO2 over time (1 hour, 6 hours).
Use the ADI line tool, R, G, B values and graph colors option (SPACIAL ANALYSIS ) to analyze data both qualitatively and quantitatively.

10. QUALITATIVE ANALYSIS

11. Open a picture, then trim the photo to increase processing time

12. Click on Full Image..
Recommended

13. Click on Trim and Use Image

14. Choose None

15. Select line tool option

16. Draw a line using a color of choice
Click these to fine tune
Placement of starting and ending points
Note beginning and ending coordinates
Note R,G, B values
Draw a line using a color of choice
Zoom in to help you
Place the beginning and ending points

17. Under file,
Select graph
colors

18. You can see all the colors or turn off some of them
to focus on just one

19. All colors off except green

20. The Value of The Control
The color graph for the control offers a baseline of R, G, B values to the student.
The next set of slides shows a sample of gelatin exposed to CO2 and its corresponding graph after 30 minutes. ADI lets you keep the settings if you are photographing the same thing over time.

24. This is a qualitative graph of diffusion
At 30 minutes, the point at which the CO2
appears to have diffused is 10/100.

25. ADI for Quantitative Analysis of Diffusion
ADI can be used to quantify diffusion as well.
The petri dish in the photo has a known diameter.
To quantify diffusion, follow the same steps for opening the photo but choose scale present in image.

30. Draw a diagonal
across the petri dish
Record actual
length

31. Draw line across gelatin
Length of gelatin line
Zoom in to help with accuracy

32. It looks like the diffusion ends
Draw a line to where
It looks like the diffusion ends
Length of diffusion line

33. Future Inquiry Possibilities
Using the Digital Camera as a data collection tool, observe how changing: temperature; density of gelatin; or concentration of the solute (CO2)--to mimic increasing CO2 levels--affects the rate of diffusion.