heat

heatGoal: to understand the nature of energy, be able to quantify the transfer of energy in a system, and perform calculations related to heat

The nature of energyEnergy is the ability to do work or produce heatThere are two types of energy:Potential- stored energy Kinetic- energy of motionChemical systems contain both types of energyEnergy is always conserved: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 temperatures

Ways to quantify HEATHeat capacity and Specific heat

Heat capacityAmount of energy needed to raise the temperature of an OBJECT 1CDepends on mass and compositionAn EXTENSIVE PROPERTY250 gram steel cylinder50 gram steel cylindergreater heat capacitywooden blockiron blockgreater heat capacity

Specific heat capacityThe amount of energy needed to raise the temperature of 1g of a substance 1CDoes not depend on size since its per gramAn INTENSIVE PROPERTYSubstance J/(goC)water 4.18ice 2.1aluminum 0.90glass 0.50iron 0.46silver 0.24Higher specific heat means more energy to raise temperature

Calculating with specific heatq=mST or q=mCT

q heat (Joules)m mass (grams)S or C specific heat (J/gC)T change in Temperature (C)

Calculating with specific heatThe temperature of a piece of copper with a mass of 95.4 g increases from 25.0 oC to 48.0 oC when the metal absorbs 849 J of heat. What is the specific heat of copper?q=mCT

C = ?m = 95.4 gT = (48.0 oC 25.0 oC) = 23.0 oCq = 849 JC = 0.387 J/goCC = q m TC = 849J 95.4 g (23.0 oC)

So now you knowEnergy (potential or Kinetic) cant be created or destroyedHeat is the TRANSFER OF ENERGYAnd you can quantify heat with heat capacity or specific heat