The point of today's lesson was to give a reason for the existence of heats of fusion and heats of vaporization. We can think of condensed matter (solids and liquids) as having a thermal energy system and a "phase energy" system. The thermal energy system is made up of all the jiggling particles and contributes to temperature. Through collisions with its particles, the thermal system can gain energy from or lose energy to its environment.
The so-called "phase system" consists of the electric fields enhanced during melting and vaporizong, a process simulated today with our computer simulations. As noted today, these fields take energy to create, and they in fact store this energy. This latent energy is not sensible; it is stored in electric fields, not jiggling particles. When condensation and freezing, particles once again bond, shedding energy to the environment, energy that comes from the now-diminshed elecric fields. The lost latent energy (aka "phase energy" or "field energy") doesn't contribute to temperature, and so there is no change in temperature during a change of phase. The jiggling is just as effective before and after the phase change, which is just another way of saying the temperature doesn't change during the phase change. Assignments:
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Physics IIMr. Swackhamer Archives
May 2019
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