3.2.1- 3.2.2 Heat Capacity (C) and Specific Heat Capacity (c); He at Capacity ( C )

1. 3.2.1- 3.2.2 Heat Capacity (C) and Specific Heat Capacity (c); Heat Capacity (C) • The amount of heat in joules required to change the temperature of an object by one degree Kelvin or Celsius; • All different objects have different C’s, because C does not take the amount of material present (mass) into account; • Three blocks of aluminum with different masses would have different heat capacities; only identical objects would have the same C; C = ΔQ/ΔT [JK-1]

2. Specific Heat [aka Specific Heat Capacity] (c) • The amount of heat in joules required to change the temperature of one kilogram of a material by one degree Kelvin or Celsius; • All objects made of the same material(s) have identical c’s, because c does take the amount of material present (mass) into account; • Three blocks of aluminum with different masses would have the same specific heat (capacities); c = ΔQ/ (m ΔT) [Jkg-1K-1]

4. Calorimeter - an insulated container which allows the mixing of materials with different temperatures and masses with minimum heat gain or loss from the surroundings (the name comes from the calorie, the amount of heat needed to raise 1 gram of water by 1 oC); For this simple line drawing of a calorimeter similar to the one used in the W-L Physics Lab, label the following parts/areas (see next page): A. the outside container, made of aluminum; B. the inside container, made of aluminum; holds and changes temp. with water; C. the insulating air space between the containers; D. the insulating fiber collar between the containers; E. the aluminum stirring paddle; F. the thermometer or temperature probe; G. mixing area for heat transfer; H. plastic insulating cover

5. E F H D B G A A C

7. EXAMPLE: A block of an unknown metal (2.10 kg) @ 90.0oC is transferred to an aluminum calorimeter (0.200 kg) holding 1.00 kg of water @ 20.0oC. After stirring, the final temperature of the metal + water + calorimeter is 60.0oC, what is the specific heat of the unknown metal? (cH2O = 4186 Jkg-1C-1 and cAl=910. Jkg-1C-1) [show solution in NB] Given: mm = 2.10 kg; mH2O = 1.00 kg; mAl = 0.200 kg; Tom = 90.0oC; Toc = 20.0oC; ToH2O = 20.0oC; cH2O = 4186 Jkg-1C-1; cAl = 910. Jkg-1C-1; Tf = 60.0oC; Unknown: cm = ? Equation: Qlost = Qgained

8. 3.2.8 (Specific) Latent Heat; Latent Heat of Fusion (Lf) - heat required to change 1.0 kg of a solid substance to a liquid at the MP; the same amount of heat is removed or released per kg at the FP (same as MP) when a liquid changes to a solid; Latent Heat of Vaporization (Lv) - heat required to change 1.0 kg of a liquid substance to a gas at the BP; the same amount of heat is removed or released at the CP (same as BP) when a gas changes to a liquid; Latent Heat of Ionization (Li) - heat required to change 1.0 kg of a gaseous substance to a plasma at the IP; the same amount of heat is removed or released at the DP (same as IP) when a plasma changes to a gas;

11. Latent Heats and problem solving. add heat to change temperature to boiling, melting, freezing point THEN add heat to change phase THEN add heat to change temperature again.

13. 3.2.10i Solve problems involving specific latent heats; How much energy must be added to 1.00 kg of ice at -10.oC to change it to water at +10.oC? (show solution in NB) [Hint: approach the problem in steps: Step 1: raise the temperature of the ice to the melting point; Step 2: melt the ice; Step 3: raise the temperature of the water from the ice to the final temp;] Given: mi = 1.00 kg; Toi = -10.0oC; Tfw = +10.0oC; ci = 2100.Jkg-1C-1; cH2O = 4186 Jkg-1C-1 ; Lfi = 3.3 x 105 Jkg-1; Unknown: ΔQtot = ? Equations:

14. Two seemingly "identical" black squares, observe what happens when ice is on them.