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This presentation covers the following topics: Understanding the Heat Capacity of Water

Activities from the ALISON Guide to Heat and Energy Activities for the Classroom Developed by Todd Hindman at the Anvil City Science Academy (Nome, AK). This presentation covers the following topics: Understanding the Heat Capacity of Water Thermal Resistance Latent Heat

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This presentation covers the following topics: Understanding the Heat Capacity of Water

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  1. Activities from the ALISON Guide to Heat and Energy Activities for the ClassroomDeveloped by Todd Hindman at the Anvil City Science Academy (Nome, AK) This presentation covers the following topics: • Understanding the Heat Capacity of Water • Thermal Resistance • Latent Heat • Temperature Gradients

  2. Add Heat • Describe the curve of the lines on your graph. Where is it the most steep? Most gradual? • If you are adding a constant amount of heat every minute, the temperature should increase at a constant rate. • Do you agree or disagree with this statement? Why? • Does our data support this statement? Explain. • Give some possible reasons why the temperatures of the two beakers did not increase at the same rate. Todd Hindman (Anvil City Science Academy, Nome AK.)

  3. Hot Rods Todd Hindman (Anvil City Science Academy, Nome AK.)

  4. Hot Rods cont. Heat is transferred from warm to cold until equilibrium is reached. Q = m xDT x sh Q = amount of heat transferred (in calories) m = mass of substance DT = temperature change (Tend – Tstart) sh = specific heat, known value for every substance (water = 1 cal/gºC) Todd Hindman (Anvil City Science Academy, Nome AK.)

  5. Hot Rods cont. So … how hot was the rod before it was put in the water? How many degrees did the water change when the rod was added? How many degrees did the metal change when added to the water? What does this mean? Todd Hindman (Anvil City Science Academy, Nome AK.)

  6. How hot was the rod? Q = m xDT x sh Q = 114 xDT x 0.11 Q = 114 x 0.11 x (35.7 – Tstart) -3078 = 114 x 0.11 x (35.7 – Tstart) -3078 = 12.54 (35.7 – T) -245.5 = 35.7 – T -281.2 = -T T = 281.2 Mass of Steel rod = 114g Specific Heat of Steel = 0.11 Todd Hindman (Anvil City Science Academy, Nome AK.)

  7. Hot Rods cont. • The HEAT CAPACITY for water and metal are different. Which has a high heat capacity? Low? • How does this relate to a lake during freeze up or thaw? • Do a lake and the air around it ever reach equilibrium? Explain. Todd Hindman (Anvil City Science Academy, Nome AK.)

  8. Thermal Resistance Todd Hindman (Anvil City Science Academy, Nome AK.)

  9. Thermal Resistance is … • The ability of a substance to resist the flow of heat through it • A measure of the insulating abilities of a substance • How quickly heat energy can pass through a substance Todd Hindman (Anvil City Science Academy, Nome AK.)

  10. Thermal Resistance Questions: • What does a negative number for Q mean? • What has a bigger thermal resistance, glass or styrofoam? • What substance may add thermal resistance to a frozen lake and cause the ice to form slower? Todd Hindman (Anvil City Science Academy, Nome AK.)

  11. Thermal Resistance of 3 Metals What does this data tell you about the thermal resistance of metals? What did you learn about thermal resistance today? (Write 2-3 sentences.) Todd Hindman (Anvil City Science Academy, Nome AK.)

  12. Temperature Gradient 500ml in tub (hot) 80ml in beaker (cold) Todd Hindman (Anvil City Science Academy, Nome AK.)

  13. Temperature Gradient • A temperature gradient is a difference in temperature across a given distance • d = distance (meters) Todd Hindman (Anvil City Science Academy, Nome AK.)

  14. Temperature Gradient Questions • How were trial 1 and trial 2 different? How were they similar? Which trial had a bigger temperature gradient? • Describe or draw the temperature gradient on a frozen lake? • How do changes in temperature gradient effect ice growth? When will ice grow the fastest? • Calculate the amount of energy in calories added to the cold water for Trial 1 and Trial 2. Show your work. • Which trial had the fastest rate of energy transfer? (hint: rate is calories divided by time to reach equilibrium) Todd Hindman (Anvil City Science Academy, Nome AK.)

  15. One More Time … 500 ml hot in tub Calculate the amount of energy in calories added to the cold water. How does this compare to Trial 1 and Trial 2? Todd Hindman (Anvil City Science Academy, Nome AK.)

  16. Latent Heat Todd Hindman (Anvil City Science Academy, Nome AK.)

  17. Latent Heat Notes • Phase Change – physcial change from one state to another (solid, liquid, gas) • Latent Heat – energy required to change the state of matter • Heat of Fusion – amount of heat needed to change a solid to a liquid • Heat of Vaporization – amount of heat needed to change a liquid to a gas Todd Hindman (Anvil City Science Academy, Nome AK.)

  18. Designing a Lake Ice Study Goal: to figure out how much heat (or energy) in calories is being transferred from the water to the atmosphere Challenge: You are being paid boo-koo bucks to design a study that will measure (on a regular basis) how much energy is leaving the lake. Questions: • What measurements do you need to take? • How will you do this? What will the procedure be? (How often? Where? With what?) • What are some potential problems with your procedure? What could mess it up? Todd Hindman (Anvil City Science Academy, Nome AK.)

  19. Heat & Ice Essay Wayne has just moved to Alaska from Texas. He is amazed by the thick layer of ice found on Alaskan lakes in the winter. Explain to Wayne why ice forms on the lake. Describe the variables that determine how thick the ice will be. ** 2-3 paragraphs, use science vocabulary! Todd Hindman (Anvil City Science Academy, Nome AK.)

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