Skittles diffusion experiment
01 // Question
How does water temperature change how fast the color diffuses off a ring of Skittles?
A testable question names one thing you change (temperature) and one thing you measure (time or distance).
02 // Variables
Independent
Water temperature- Cold water
- Room-temperature water
- Warm water
Dependent
Time for colors to reach the center- Seconds until colors meet in the middle
- Distance colors travel in 60 seconds
03 // Hypothesis
IF warmer water is used to soak a ring of Skittles, THEN the color will reach the center of the plate faster, BECAUSE warmer water molecules move faster and collide with the dye more often, speeding up how fast it dissolves and spreads.
04 // Procedure
1. Arrange the ring
Place Skittles around the inside edge of a white plate, alternating colors evenly.
2. Measure the water
Measure the same volume of water at each test temperature (cold, room temperature, warm).
3. Pour carefully
Slowly pour the water into the center of the plate without disturbing the candies.
4. Time the spread
Start a stopwatch immediately and time how long it takes for the colors to meet in the middle.
5. Record and repeat
Record the time, dry the plate, and repeat with a fresh set of Skittles at the next temperature.
05 // Data table
| Water temperature | Trial 1 (s) | Trial 2 (s) | Colors reached center? |
|---|---|---|---|
| Cold | ____ | ____ | ____ |
| Room temperature | ____ | ____ | ____ |
| Warm | ____ | ____ | ____ |
06 // What to expect
Warm water usually pulls the color off the candy shell and spreads it toward the center fastest, because heat speeds up the random motion of water molecules, which speeds up diffusion — the process of a substance spreading from an area of high concentration to low concentration.
The colors stay separated in distinct bands instead of mixing into brown, because each dye diffuses outward from its own candy at roughly the same rate and meets the others in the middle before they've had time to blend.
07 // Lab notes
- Pour the water gently in the very center — pouring near the candies creates currents that move color faster for reasons that have nothing to do with temperature.
- Use a completely dry, clean plate for each trial so leftover color doesn't skew the timing.
- This lab uses only food and water — low hazard, but avoid eating candy that has already been in the test water.
08 // Remember
Diffusion is faster when molecules move faster. Heat speeds up molecules, so warm water diffuses color quicker.
09 // Questions people ask
Why does the color spread faster in warm water?
Heat gives water molecules more kinetic energy, so they move and collide faster. Those faster collisions pull the dye off the candy's shell and carry it through the water more quickly — a direct demonstration of how temperature affects the rate of diffusion.
Why don't the Skittles colors mix into brown in the middle?
Each color diffuses outward from its own candy at a similar rate, so the bands of color meet at roughly the same time without fully blending. Diffusion moves a substance from high to low concentration, but it doesn't erase the boundary instantly — that takes much longer than a classroom demo runs.
What is being measured in the Skittles diffusion experiment?
The most common dependent variable is the time it takes for the color to travel from the candies to the center of the plate, though some versions measure how far the color has spread after a fixed time instead.