2. 1

3. Temperature and Heat Temperature is the measurement of the avg. KE of the molecules in a material. Heat is the transfer of KE from one material to another. 3

4. 4

5. 5

6. Conduction The transfer of thermal energy in solids. Materials must be in direct contact with each other! Ex: Heating of the bottom of a pot on stove. Clip 6

8. Convection Transfer of thermal energy in liquids and gases.Transfer of thermal energy in liquids and gases. Matter actually moves from one place to another.Matter actually moves from one place to another. clip 7

9. Radiation Transfer of thermal energy by electromagnetic wavesTransfer of thermal energy by electromagnetic waves Transferring energy through space... NO MATTER IS REQUIRED!Transferring energy through space... NO MATTER IS REQUIRED! ClipClipClip 8

11. Exothermic and Endothermic Reactions A reaction in which heat is given out is exothermic. A reaction in which heat is taken in is endothermic. https://www.youtube.com/watch?v=mamoT11TEV4 https://www.youtube.com/watch?v=cVydmlz0F-E https://www.youtube.com/watch?v=GQkJI-Nq3Os https://www.youtube.com/watch?v=L-G7pLufXA o

12. Specific Heat Adding Energy to a material Causes the temperature to go up. Taking energy away from a substance causes the temp. to go down! 10

13. Have you ever noticed that on a hot summer day the pool is cooler than the hot cement? OR maybe that the ocean is cooler than the hot sand? Why? The sun has been beating down on both of them for the same amount of time........... It takes more thermal energy to raise the temperature of water that it does the cement! 11

14. Water absorbs a lot of heat energy before its temperature changes while sand needs little heat energy before its temperature increases. 12 https://www.youtube.com/watch?v=UtyyUHJGsUY

17. 16 Examples of Specific Heats

18. Specific Heat The amount of energy required to raise the temperature of a material (substance) by 1°C. It takes different amounts of energy to make the same temp. change in different substances. We call the amount required: Specific Heat (C p )! 15

19. Specific Heat of water The Cp is high because H 2 O mols. form strong bonds w/each other. It takes a lot of energy to break the bonds so that the the molecules can then start to move around faster (HEAT UP). 16

20. Example: Specific Heat of Water Cp = 4,184 Joules of energy to raise the temperature of 1kg 1°C. video clipvideo clipvideo clipvideo clip Why C p ? C p Stands for “Heat Capacity” 17

21. Calculating Specific Heat The Greek letter Δ means “change in” 18

22. 21 A hot-water bottle contains 750. g of water at 65.0 °C. If the water cools to body temperature (37.0 °C), how many calories of heat could be transferred to sore muscles? STEP 1 Given: 750 g of water cools from 65 °C to 37 °C SH water = 1.00 cal/g °C Need: calories of heat transferred STEP 2 Calculate the temperature change  T: 65 °C – 37 °C = 28 °C Sample Calculation for Heat

23. 22 STEP 3 Write the heat equation: Heat (cal) = mass(g) x  T x SH STEP 4 Substitute given values and solve for heat: 750 g x 28 °C x 1.00 cal g °C = 21 000 cal Sample Calculation for Heat

24. 23 Learning Check How many kilojoules are needed to raise the temperature of 325 g of water from 15.0 °C to 77.0 °C? 1) 20.2 kJ 2) 84.3 kJ 3) 105 kJ

25. 24 2) 84.3 kJ STEP 1 Given: 325 g of water warms from 15.0 °C to 77.0 °C C water = 4.184 J/g °C 1 kJ = 1000 J Need: kilojoules of heat needed STEP 2 Calculate the temperature change  T: 77.0 °C – 15.0 °C = 62.0 °C STEP 3 Write the heat equation: Heat (joules) = mass (g) x  T x SH

26. 25 Solution (continued) STEP 4 Substitute given values and solve for heat:

27. A copper ornament has a mass of 0.0693 kg and changes from a temperature of 20.0°C to 27.4ºC. How much heat energy did it gain? A 200 J C 540 J 24 B 460 J D 740 J

28. Your Turn!! Show me your work, correct rounding and units!! 1.What is the specific heat of a substance that absorbs 2500. joules of heat when a sample of 100. g of the substance increases in temperature from 10.0 °C to 70.0°C? 2.If 200. grams of water is to be heated from 24.0°C to 100.0°C to make a cup of tea, how much heat must be added? The specific heat of water is 4.184 J/g∙C 3.How many grams of water would require 2200. joules of heat to raise its temperature from 34.0°C to 100.0°C? The specific heat of water is 4.184 J/g∙C 4.A block of aluminum weighing 140. g is cooled from 98.4°C to 62.2°C with the release of 1080. joules of heat. From this data, calculate the specific heat of aluminum. 5.100.0 g of 4.00°C water is heated until its temperature is 37.0°C. If the specific heat of water is 4.184 J/g°C, calculate the amount of heat energy needed to cause this rise in temperature.