Diffusion (Christian Pirijanian)
Title: Diffusion with Dye and Tea: The Movement of Molecules with Respect to Thermal Kinetic Energy
Principle(s) Investigated: Diffusion of molecules from a high to low gradient, and how thermal kinetic energy can influence the phenomena
Standards:
HS-LS1-3.
Plan and conduct an investigation to provide evidence that feedback mechanisms maintain homeostasis.
Materials: Tea bags, hot plate, ice, Styrofoam container, cups, water, dye
Procedure:
Part 1:
1. Obtain 2 breakers each filled with 300 ml of water
2. Heat up 300 ml of water in a beaker to 200 degrees Fahrenheit. Chill another beaker of 300 ml of water on ice in a Styrofoam container. Keep another beaker filled with 300 ml of water at room temperature.
3. Drop 3 drops of colored dye into each beaker filled with water and observe diffusion. Make comparison of how the dye disperses through the water
Part 2:
1. Obtain 2 cups with 200 ml of water, one with water heated to 200 degrees Fahrenheit, another with water at room temperature.
2. Obtain 2 tea bags. Steep one tea bag into each cup for 2-3 minutes
3. Observe differences in cups over the time period.
Student prior knowledge: The definition of a molecule and that they comprise other objects
Explanation: Students will observe the diffusion of molecules in dye and tea through water, from a high to low concentration. Students will also see that high thermal kinetic energy can speed up the process, while low thermal kinetic energy can slow the process down. Lastly, students will understand that larger molecules diffuse slower than smaller molecules (pigments, which are larger compared to smaller aromatic compounds).
Questions & Answers:
Describe how the dye molecules and the molecules in the tea moved through the water.
-They moved from a high concentration to a low concentration.
How does raising the thermal kinetic energy affect the diffusion of the molecules?
-It increases it, by increasing the vibrations and movement of the dye/tea molecules.
There are many different molecules of various sizes in tea leaves. Why might tea that is steeped for a shorter time taste less bitter?
-Molecules that are responsible for bitter taste (tannins) take longer to diffuse than other aromatic compounds.
Applications to Everyday Life:
-The molecules in colognes and perfumes make their way from a high concentration (the bottle and spray nozzle) to a low concentration (ideally your body if you aimed correctly). They then diffuse off over time in the same fashion.
-Adding heat to cooking allows many of the molecules responsible for taste to be dispersed into the meal you are cooking, such as the aromatic molecules in beats entering soup when cooking borscht.
-Essential monomers used in physiological processes diffuse from your intestines (high concentration) to your blood (low concentration).
Photographs/Diagrams:
Videos:
Diffusion of dye under different temperatures
Diffusion of tea under different temperatures
References: