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Monday and Tuesday April 16 and 17

Monday and Tuesday April 16 and 17. Chapter 10: Thermodynamics. What is energy? Is there a difference between heat and temperature?. Heat Energy flow caused by a temperature difference Measured in J or cal 1 cal = 4.184 J. Temperature Measure of random motion of a substance

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Monday and Tuesday April 16 and 17

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  1. Monday and TuesdayApril 16 and 17

  2. Chapter 10:Thermodynamics What is energy? Is there a difference between heat and temperature?

  3. Heat Energy flow caused by a temperature difference Measured in J or cal 1 cal = 4.184 J Temperature Measure of random motion of a substance Measured in ̊C, ̊F, or K

  4. Calculations • Convert temperature • Change in temperature • Convert to grams of a substance • Q=SM∆T

  5. Converting T ( ̊F to ̊C) Fahrenheit to Celsius T ( ̊C) = ( T(°F) – 32) x (5/9) Ex: Convert 65 ̊F to ̊C T ( ̊C) = ( T(°F) – 32) x (5/9) T ( ̊C) = ( 65 °F – 32) x (5/9) T ( ̊C) = 18. ̊C

  6. Change in T (∆T) ∆T = T final – T initial Ex: If a cup of boiling water is left on the counter until it comes to room temperature (20 ̊C), what is the change in temperature? ∆T = T final – T initial ∆T = 20 ̊C – 100 ̊C ∆T = -80 ̊C

  7. Convert to grams (from mol) Convert 6.00 mol of H2O to grams. 108. g H20

  8. Q = SM∆T Q = Energy (heat) required in Joules S = specific heat capacity in J/g̊C M = mass of the sample in grams ∆T = change in temperature in ̊C

  9. Specific Heat Capacity The amount of energy required to raise the temperature of one gram of a substance by one degree Celsius.

  10. Heat transfer How can people walk on hot coals? http://www.youtube.com/watch?v=3ToRsSYSkbY

  11. Specific Heat Capacity The amount of energy required to raise the temperature of one gram of a substance by one degree Celsius.

  12. Q = SM∆T How much energy is needed to warm 7.40 g of water from 17.0 ̊C to 35.0 ̊C? Q = want S = 4.184 J/g̊C (from table) M = 7.40 g ∆T = 35.0 ̊C – 17.0 ̊C= 18.0 ̊C

  13. Recommended Reading Homework: Thermo WS 1 10.2 (pg 291 – 292) 10.5 (pg 294 – 300) Practice Problems Pg 318 - 320 # 6-10, 22-28, 49-58 Rewrites are due Friday, 4/20 Extra credit assignment due 5/11

  14. Wednesday and ThursdayApril 18 and 19

  15. Warm UP How much energy is needed to warm 3.60 g of lead from 17.0 ̊C to 35.0 ̊C? Q = want S = 0.128 J/g̊C (from table) M = 3.60 g ∆T = 35.0 ̊C – 17.0 ̊C= 18.0 ̊C

  16. Review Homework

  17. Review Homework

  18. Practice Problem How much energy is introduced in to 1.0 kg of ice at -20.0°C, to turn it into steam at 110.0°C? Q = want S = 2.03 J/g̊C (from table) M = 1.0 x 103 g ∆T = 110.0 ̊C – -20.0 ̊C= 130.0 ̊C

  19. Calorimeter Calorimeter is a heat measuring device. The calorimeter is generally used to measure the amount of heat energy transferred during a reaction. Using this information, one can calculate the specific heat of a substance or other heat related information. Stirrer Thermometer Water Metal pieces Insulated container

  20. Calorimeter A closed system in which energy is maintained. -(Q 1) = Q 2

  21. Calorimeter If a 30.0 g block of iron is put into the calorimeter and -9.87 J of energy is released, how much energy does the water take on?

  22. Practice Problems A sample of aluminum (0.895 J/g °C )at 75.0°C was placed in a calorimeter containing 25.0 grams of water at 20.0°C. The temperature stopped changing at 29.4°C. What is the mass of the sample? -(Q 1) = Q 2 -(SmetalMmetal∆Tmetal )= SwaterMwater∆Twater

  23. Practice Problems A 4.57 g sample of metal is heated to 57.8 ̊C and placed in 150. mL of water that is at 20.0 ̊C. The temperature of the water increases to 40.0 ̊C. What is the specific heat capacity of the metal? -(Q 1) = Q 2 -(SmetalMmetal∆Tmetal )= SwaterMwater∆Twater

  24. Practice Problems A 8.13 g sample of iron is heated to 45.4 ̊C and placed in 400. mL of water that is at 23.0 ̊C. What will the final temperature? -(Q 1) = Q 2 -(SmetalMmetal∆Tmetal )= SwaterMwater∆Twater

  25. Practice Problems A 7.01 kg sample of iron is heated to 69.4 ̊C and placed in 6.71 L of water. The final temperature of the water is 39.8 ̊C. What is the initial temperature of the water? -(Q 1) = Q 2 -(SmetalMmetal∆Tmetal )= SwaterMwater∆Twater

  26. Homework and Reminders Homework: Thermo WS 2 Reminders: Rewrites are due FRIDAY, 4/20 Extra credit due 5/11

  27. FridayApril 20

  28. REWRITES DUE If you rewrote your Lab 3.21 for proficiency, turn in the highlighted rewrite and the original paper to the turn in bin.

  29. Warm Up If 150.0 grams of iron at 95.0 °C, is placed in an insulated container containing 500.0 mL of water at 25.0 °C, and both are allowed to come to the same temperature, what will that final temperature be?

  30. Review Homework

  31. Review Homework

  32. Quiz Time Clear desk except a pencil and calculator

  33. Thermodynamics Lab Purpose: Determine the specific heat capacity of an unknown metal and identify the metal. Complete the prelab assignment BEFORE class. Dress appropriately for lab

  34. Notes for the lab • Don’t poke the thermometer through the cups • Put metal in water and cover as quickly as possible

  35. Homework and Reminders Homework: Thermo WS 3 Thermo prelab Reminders: Rewrites are due FRIDAY, 4/20 No exceptions

  36. Monday and TuesdayApril 23 and 24

  37. Warm Up In a calorimeter 187 mL of 18.9 ̊C water is mixed with a 4.32 g block of 92.0 ̊F granite. What will the final temperature be?

  38. Review Homework

  39. Review Homework

  40. Lab Time • Don’t poke the thermometer through the cups • Put metal in water and cover as quickly as possible

  41. Done in lab? ◦Work on write up Title, purpose, data tables, calculations, analysis If you finish the lab turn it in to the turn in bin, if not it is your homework ◦Work on practice test if you finish the lab

  42. Reminders Homework: Thermo Lab Write Up GeneralReminders: Extra Credit due 5/11 Thermodynamics Test 4/25 and 4/26

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