Press the bar of soap firmly against a plate moistened with water and turn it several times.

Press the bar of soap firmly against a plate moistened with water and turn it several times. Raise the soap up. the plate rises along with the soap. Explain why this happened.

This is due to the mutual attraction of the dish molecules and the soap and water molecules. The attraction between molecules becomes noticeable only when they are very close to each other, at a distance comparable to the size of the molecules (atoms) themselves.

The dry soap will not stick to the plate because the molecules of the soap and the plate are far apart. When the soap is wet, then the water molecules mixed with the soap can approach the plate molecules, at a distance comparable to these molecules.