Question

Phase changes: Identify a substance that can exist in all phases here on Earth. Describe different phase changes and what happens to this substance at the atomic level during these phase changes.

Answer 1

One good example of the substance that can exist in all the phases on earth is water, below zero degree centigrade temperature at 1 atm pressure , water exist in the solid phase region as ice, above 100 degree centigrade water exist as vapours, and at still higher temperature temperature water gets converted to superheated steam. At atomic level with changes in temperature the thermal energy of molecules gets altered for example if we heat the piece of ice in a water bath, the molecules of water which occupy definite position in the solids starts vibrating when the thermal energy increases hence, the molecules becomes loosely bound with further rise in temperature and gets converted into the liquid state. So with increase in temperature the thermal energy increases of the molecules increases.