Apps ≫ Diffusion Canvas

1. Put on gloves and place cotton pieces in a cross shape on each plate, spacing three pieces evenly from the outside in.
2. Pour a small amount of phenolphthalein and BTB solution onto each plate, dropping enough to soak the cotton.
3. Use a pipette to drop ammonia water into the center of each plate.
4. Observe how the colors change.
5. (Result) You can observe the cotton pieces changing to red and blue in sequence, starting from the ones closest to the ammonia water.
6. Afterward, feel free to experiment using the large rectangular plate.

The reason the cotton pieces turn red and blue starting from those closest to the ammonia: This is because ammonia particles move on their own and diffuse in all directions.