Molecules move from areas of high concentration, where there are lots of other similar molecules, to areas of low concentration, where there are fewer similar molecules in a process called DIFFUSION. When the molecules are evenly spread throughout the space, they have achieved EQUILIBRIUM.
Lots of things can affect how fast molecules diffuse, including temperature. When molecules are heated up, they vibrate faster and move around faster, which helps them reach equilibrium more quickly than they would if it were cold. Diffusion takes place in gases like air, liquids like water, and even solids.
You can watch food coloring molecules diffuse into gelatin (a colloid) when you do this fun, edible Halloween experiment.
Dissolve two 3oz packages of lemon Jell-O in 1 and 1/4 cups of boiling water. (Adult supervision required.) Allow it to cool briefly, and pour it into 2 ice-cube trays with oval-shaped holes. Refrigerate until firm.
Dissolve one 6oz package of Berry Blue Jell-O in 1 and 1/4 cups of boiling water. Cool briefly.
Using the end of a potato peeler or a strawberry corer to hollow out a circle in the middle of each yellow Jell-O “eyeball.” Carve the circle about halfway to the bottom of the gelatin. Use a toothpick or skewer to remove the Jell-O.
Fill the hollow with melted blue gelatin and return to the refrigerator to harden. The blue Jell-O will be the pupil of the eye.
Set ice cube trays containing Jell-O in a casserole dish of hot tap water for 1-2 minutes. Turn upside down in another dish to un-mold and then move your eyeballs to another serving dish.
Use a straw to add Kool-Aid liquid (like Cherry) to the center of each eyeball. Then, use a sharp skewer to draw lines out from the center.
Cover with plastic wrap and let sit for a few hours so the Kool-Aid will start to diffuse.
Add a second color Kool-Aid drops (Like Blue Raspberry) to the center of the eye and repeat.
Cover and refrigerate until ready to serve. The Kool-Aid colors will continue to diffuse into the eyeballs!