Latent Heat

Discussion

discussion

Name the 6 major phase changes (including synonyms).

Heat absorbed or released as the result of a phase change is called latent heat. There is no temperature change during a phase change, thus there is no change in the kinetic energy of the particles in the material. The energy released comes from the potential energy stored in the bonds between the particles.

• exothermic (warming processes)
  • condensation
    • warmer in the shower
    • steam radiators
  • freezing
    • orange growers use ice to stop oranges from freezing
  • deposition
    • snowy days are warmer than clear days in the winter
• endothermic (cooling processes)
  • evaporation/boiling
    • sweat
    • alcohol is "cool"
  • melting
    • melting ice in drinks
  • sublimation
    • cooling with dry ice

Q = mL

Scattered thoughts…

• Under extreme conditions of heat and exercise, an individual may sweat more than a liter of liquid per hour.
• The interior of roasted meat can never reach temperatures higher than the boiling point of water until all the water is cooked out of it, at which point it would resemble shoe leather. The outside is quickly dried out, however, and can reach the temperature of the surrounding cooking medium.
• Cocoa butter is unique among the fats in that it is very regular in composition; whereas most other fats are actually mixtures. This gives it a very definite point; unlike butter, which softens gradually. As it melts in your mouth, it absorbs latent heat. This makes chocolate bars taste "cool". Cocoa butter is remarkably uniform in composition and structure: only three fatty acids in the majority of its triglycerides, with the same one occupying the middle position. Pure cocoa butter is quite brittle up to about 34 ℃ (93 ℉), at which point it melts quite quickly.