1. T HERMOCHEMISTRY

2. E NERGY OF P HASE C HANGES : H EATING C URVE DURING PHASE CHANGES TEMPERATURE IS CONSTANT!!!!! Energy Increases!

3. E NERGY OF P HASE C HANGES : C OOLING C URVE What would a cooling curve look like? Energy Decreases!

4. T HERMOCHEMISTRY NOTES

5. T HERMOCHEMISTRY  study of the transfer of energy as heat that accompanies chemical reactions and physical changes

6. H OW CAN HEAT MOVE IN A REACTION ?  Exothermic:  Heat is released (exits)  Feels warm  Endothermic:  Heat is absorbed (enters)  Feels cold

7. S PECIFIC H EAT  Energy transferred depends on:  The material  The mass  Specific Heat: amount of energy required to raise the temperature of one gram by one Celsius degree (1°C) or one kelvin (1 K).  Unit: J/(g°C)

8. H EAT T RANSFER E QUATION Q = m c Δ T Q = energy lost or gained m = mass of the sample c = specific heat at a given pressure ∆T = difference between the initial and final temperatures.

9. E XAMPLE P ROBLEM  How much heat is absorbed when an 869g iron bar cools from 94 o C to 5 o C? specific heat for iron is: 0.444 J/(g o C) Equation: Q = m c Δ T

10. M EASURING H EAT T RANSFER open closedisolated SYSTEMSURROUNDINGS System: specific part of an experiment that is being studied

11. C ALORIMETRY  Calorimeter: instrument used to measure heat absorbed or released.  Energy released from the reaction is measured from the temp change of the water