2. HEAT GOAL: TO UNDERSTAND THE NATURE OF ENERGY, BE ABLE TO QUANTIFY THE TRANSFER OF ENERGY IN A SYSTEM, AND PERFORM CALCULATIONS RELATED TO HEAT

3. THE NATURE OF ENERGY is the ability to do work or produce heatEnergy is the ability to do work or produce heat There areThere are two types of energy: stored energyPotential- stored energy energy of motionKinetic- energy of motion Chemical systems contain both types of energyChemical systems contain both types of energy Energy is always conserved:Energy is always conserved: Law of conservation of energy: energy can neither be created or destroyed but can be transformed (stored or transferred)Law of conservation of energy: energy can neither be created or destroyed but can be transformed (stored or transferred) HEAT: is the transfer of energy (Calories or joules) due to differing temperaturesHEAT: is the transfer of energy (Calories or joules) due to differing temperatures is the ability to do work or produce heatEnergy is the ability to do work or produce heat There areThere are two types of energy: stored energyPotential- stored energy energy of motionKinetic- energy of motion Chemical systems contain both types of energyChemical systems contain both types of energy Energy is always conserved:Energy is always conserved: Law of conservation of energy: energy can neither be created or destroyed but can be transformed (stored or transferred)Law of conservation of energy: energy can neither be created or destroyed but can be transformed (stored or transferred) HEAT: is the transfer of energy (Calories or joules) due to differing temperaturesHEAT: is the transfer of energy (Calories or joules) due to differing temperatures

4. WAYS TO QUANTIFY HEAT HEAT CAPACITY AND SPECIFIC HEAT

5. HEAT CAPACITY OBJECTAmount of energy needed to raise the temperature of an OBJECT 1 ° C Depends on mass and composition An EXTENSIVE PROPERTY OBJECTAmount of energy needed to raise the temperature of an OBJECT 1 ° C Depends on mass and composition An EXTENSIVE PROPERTY 250 gram steel cylinder 50 gram steel cylinder greater heat capacity wooden block iron block greater heat capacity

6. SPECIFIC HEAT CAPACITY The amount of energy needed to raise the temperature of 1g of a substance 1 ° C Does not depend on size since it’s per gram An INTENSIVE PROPERTY The amount of energy needed to raise the temperature of 1g of a substance 1 ° C Does not depend on size since it’s per gram An INTENSIVE PROPERTY Substance J/(g o C) water 4.18 ice 2.1 aluminum 0.90 glass 0.50 iron 0.46 silver 0.24 Higher specific heat means more energy to raise temperature

7. CALCULATING WITH SPECIFIC HEAT q=mS∆T or q=mC∆T q  heat (Joules) m  mass (grams) S or C  specific heat (J/g ° C) ∆T  change in Temperature ( ° C)

8. CALCULATING WITH SPECIFIC HEAT The temperature of a piece of copper with a mass of 95.4 g increases from 25.0 o C to 48.0 o C when the metal absorbs 849 J of heat. What is the specific heat of copper? q=mC∆T C = ? m = 95.4 g ∆T = (48.0 o C – 25.0 o C) = 23.0 o C q = 849 J C = 0.387 J/g o C C = q m ∆T C = 849J 95.4 g (23.0 o C)

9. SO NOW YOU KNOW… ENERGY (POTENTIAL OR KINETIC) CAN’T BE CREATED OR DESTROYED HEAT IS THE TRANSFER OF ENERGY AND YOU CAN QUANTIFY HEAT WITH HEAT CAPACITY OR SPECIFIC HEAT