Volcanofest: Outreach Fair Demonstrations Handbook

Clocks in Rocks: Visualizing Diffusion With Gelatin
Rebecca deGraffenried 1,2 , Maria Dias 2 , Linda Sobolewski 2 , Andrea Tonato 3 , William Nelson 3 , Nabila Nizam 3 , &
Tom Shea 3
Keywords
1
Arizona State University
2
Ruhr-Universität Bochum
3
University of Hawai‘i at Mānoa
Add up to ten keywords to describe your activity; Keywords could include suggested educational
levels, topics the activity is applicable for, or if the activity needs to be completed outside
Summary of the activity
Hands-on Activities
This activity uses food coloring in gelatin to visualize the process of diffusion, which is important in
the geosciences for determining the timescales of processes. Colored gelatin is layered on top of
non-colored gelatin, and over the course of a few hours to a day, the once-sharp boundary between
the two “blurs” as food coloring diffuses into the non-colored gelatin. Different parameters can be
changed to investigate how they influence the speed at which the food coloring diffuses, such as the
surrounding temperature (e.g., room temperature vs in a refrigerator), the color of the food
coloring, and the concentration of the food coloring. The speed of diffusion can be qualitatively
compared between experiments or quantitatively measured by using observations to solve diffusion
equations.
Target Audience The qualitative comparison of diffusion speeds is applicable for all audiences, but
the quantitative determination of diffusion speed is applicable for advanced high schoolers and
above.
Learning Goal(s)
1. Visualize the process of diffusion to better understand how it works and how it can be used to
calculate timescales of geologic processes
2. (Qualitative) Understand how different parameters change the speed of diffusion
3. (Quantitative) Understand and apply the diffusion equations
Required Materials and Instructions
Details of the needed materials, instructions, and relevant background for diffusion chronometry in
volcanology can be found at: https://www.rldegraffenried.com/gelatin-diffusion.html
4
5