Diffusion of a Dye in Hot and Cold Water

Purpose:  The purpose of this experiment is to demonstrate the principle of diffusion.  Diffusion is the net movement of particles (atoms, ions, or molecules) from an area of greater concentration to areas of lesser concentration.

Materials and Methods:  For this experiment, the student will require a projector, two petri dishes, two 150 ml beakers, hot plate, potassium permanganate (purple dye), and a spatula.  Obtain about 50 ml of cold water in one beaker and about 50 ml or boiling water in the other.  Place the petri dishes on the projector and add cold water to one dish and boiling water to the other.  Allow the water in the dishes to become still.  Using the spatula, add a crystal of potassium permanganate to the center of each dish. 

Experiment:  Observe the experiment for several minutes and note what happens to the purple dye in each petri dish.

Conclusion:  Do you observe diffusion in each?

How does the rate of diffusion differ?

Why is there a greater rate of diffusion in one?

(return to menu)