A student heats a small amount of water in an open metal flask until it boils and the flask is filled with steam.
Describe what happens to the motion and kinetic energy of the water molecules as the water is heated.
Describe how the arrangement and spacing of the molecules in the steam differ from those in the liquid water.
The student seals the flask tightly with a rubber bung and then pours cold water over the outside. The flask collapses inwards. Explain, in terms of molecules and pressure, why the flask collapses.