Evidences of Heat Transfer Change in temperature Change of state Change in amount
Change in Temperature The amount of heat supplied is directly proportional to the change in temperature. E = heat θ = temperature k = constant
Thermal Capacity The amount of heat required to change the temperature of a substance by 1 C °.
Factors affecting Thermal Capacity The amount of substance Mass Symbol: m Unit: kg The greater the mass, the more heat required The type of substance Property Specific heat capacity Symbol: c Units: J/kg-K or J/kg-C ° The greater the c, the more heat required
Specific Heat Capacity The amount of heat required to change the temperature of a kilogram of substance by 1 C °. Tells how difficult it is to change the temperature of a substance
Specific Heat Capacities of some substances
Water is used as heating fluid in radiators. Water is in a hot compress England is green. Pies make you cry.
Quantifying Heat (with change in Temperature) Joule meter Page 89, SQ Sample Problems
Change of State Process when a substance changes from solid to liquid Melting At constant temperature Melting point Solidification/Fusion Process when a substance changes from liquid to solid At constant temperature Freezing point
Change of State Process when a substance changes from liquid to gas Vaporization At constant temperature Boiling point Condensation Process when a substance changes from gas to liquid At constant temperature Dew point
Boiling versus Evaporation BoilingBoiling EvaporationEvaporation Occurs at a specific temperature Occurs at any temperature Occurs inside the liquid Occurs at the surface Change from liquid to gas
Quantifying Heat (with change of state) Joule meter Page 89, SQ Sample Problems L = Latent Heat Latent HeatLatent Heat Unit: J/kg
A 500 g piece of aluminium is heated with a 500 W heater for 10 minutes. (a) How much energy will be given to the aluminium in this time? (b) If the temperature of the aluminium was 20°C at the beginning, what will its temperature be after 10 minutes? Leveling Up
Latent Heat The amount of heat required to change the state of a kilogram of a substance. Latent heat of fusion for liquid to solid and vice versa Latent heat of vaporization for liquid to gas and vice versa
Latent Heat Used to break molecular bonds Changes potential energy No change in kinetic energy