1. Thermochemistry The Basics of Heat Transfer

2. The Flow of Energy Thermochemistry - concerned with heat changes that occur during chemical reactions

3. Cranking up the Heat: Basic Thermodynamics Energy - capacity of an object to do work or produce heat

4. Kinetic Energy  The energy an object has due to its motion Potential Energy  Stored energy  Energy of position

5. Energy in the universe is constant, though it changes forms. Law of Conservation of energy Law of Conservation of energy – energy can neither be created nor destroyed

6. Heat vs. Temperature Temperature and heat are not the same thing. Temperature describes the amount of motion of particles (the higher the temp., the faster the particles move because they have more energy). Heat describes amount of energy transferred from one object to another

7. Describing Energy Changes Heat flow is from the warmer object to the cooler object Heat Flow

8. Describing Energy Changes Hot day 50°C = 122°F Beans lost energy, it was transferred to its surroundings. This change of energy would be negativechange = ∆ Energy transferred from fire to beans. Change in energy for beans would be positive.

9. Endothermic reactions – absorbs heat, ∆E is positive, the surroundings cool down Exothermic reactions – releases heat, ∆E is negative, the surroundings heat up Heat Surroundings Heat Surroundings Describing Energy Changes Feels cold to the touch Feels warm to the touch

10. Units used to describe Energy: calorie – called “little calorie” – (cal) kilocalorie – called “Big calorie”- (CAL)  1000 calories – same as a food calorie Joule – the SI unit of heat - (J)

11. CONVERSION FACTOR 1 cal = 4.184 joules 1 cal4.184 J 4.184 J 1 cal

12. Heat Units: Conversion Problems 1. Convert 32.7 cal to joules. 2. Convert 6.24 J to cal. 3. Convert 10.2 Cal to cal. 4. Convert 10.2 Cal to joules. 5. Convert 8.16 joules to Cal.