Chemistry Homework help

1. Phase Changes By: Abhinand Sivaprasad

2. MELTING • Melting • Melting, or fusion, is a physical process that results in the phase change of a substance from a solid to a liquid. The melting point of any substance is when a substance starts to melt. Let us take an experiment as an example. Say there is ice being heated up from C. At this time the heat energy is used to raise the temperature of the ice. Once it reaches C, the heat energy is used towards the phase change, (i.e.) towards change in the molecular structure from solid to liquid.

3. SUBLIMATION • Sublimation • Sublimation is the transition of a substance from the solid phase to the gas phase without undergoing intermediate change to liquid. Sublimation is a phase transition that occurs at temperatures and pressures under the triple point. With material such as ice, sublimation will not occur (i.e.) at the normal pressure and temperature.

4. EVAPORATION/BOILING • Evaporation/Boiling • Evaporation is a type of vaporization of a liquid, which occurs only on the surface of a liquid. The other kind of vaporization is called boiling. Boiling is often mistaken for evaporation, but they are different. As mentioned before evaporation occurs on the surface of a liquid. Boiling, however takes place in the entire mass of the liquid.

5. CONDENSATION • Condensation • Condensation is the change in the phase of matter from the gaseous phase into liquid droplets of solid particles of the same element. For the object to be condensable its pressure must be between the triple point pressure to the critical point pressure in the phase diagram.