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Warm Up WS #2 OUT!

EQ: How do we solve 1-step and 2-step energy problems? HOT Q1: What are the three formulas? HOT Q2: How do I know it’s a 2-step problem? HOT Q3: Would Ms. Hoffman give a pop quiz?. Warm Up WS #2 OUT!. What phase is Region B? 2. Identify the change happening and appropriate formula:

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Warm Up WS #2 OUT!

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  1. EQ: How do we solve 1-step and 2-step energy problems? HOT Q1: What are the three formulas? HOT Q2: How do I know it’s a 2-step problem? HOT Q3: Would Ms. Hoffman give a pop quiz? Warm Up WS #2 OUT! • What phase is Region B? 2. Identify the change happening and appropriate formula: Water vapor in the room condenses on a cold surface A B C

  2. Agenda • Warm-Up • Agenda • Trickier Quantitative Energy Problems • Pop Quiz • Exit Ticket HOMEWORK: FINISH WORKSHEET 1, 2, and 3

  3. Take out notes from yesterday!

  4. Steps • What changes are taking place? (Is temperature changing? Is phase changing?) 2. Which heat equation? • Identify variables. • Plug in and solve.

  5. Yesterday we learned Steps #1 and #2. • Today we will learn Steps #3 and #4!

  6. Example • A cup of hot chocolate (270 g) cools from 60˚C down to comfortable room temperature 20.˚C. How much energy does it release to the surroundings? ΔT = l Tfinal – Tinitial I What is the “absolute value”?

  7. 2. A 110 g cup of water spills on your kitchen floor. If all of the water evaporates, how much energy did the water absorb from the surroundings?

  8. You accidentally left your flavor-ice popsicle, with a mass of 43g at 0˚C,on a park bench during the summer. By the time you got back from the basketball court it is totally melted. How much energy must be absorbed by the ice in order for it to melt all the way? (assume no temperature change)

  9. 4. A cup of water, 270 g, at 100C evaporates when left outside on a summer day. How much energy did the cup of water absorb? (assume no temperature change)

  10. Practice • 5. You are heating water on your stove to make some Jello. A mass of 345g warms from room temperature (20˚C ) to 80˚C. How much energy needed to be absorbed by the water in order to warm the water?

  11. 6. An ice cube tray with a mass of water of 560g is placed in a freezer. How much energy must be released into the freezer and out the back of the refrigerator in order to freeze the ice cubes in the tray?

  12. Two-Step! • Trickier quantitative energy problems… • Like your dollar bill, with hard work, you too will be on FIRE!!!

  13. Two-Step 10) A 50.0 g sample of liquid water at 0.0˚C ends up as ice at – 20.0 ˚C. How much energy is involved in this change?

  14. You begin with a 75g glass of 50°C water. You cool it to 0°C and then completely freeze it. How much energy was lost?

  15. Daniel has 25g of water at 80°C and boils it completely into gas. How much energy was lost?

  16. Pop Quiz! • No talking • Only logistical questions will be answered • Good luck!!!

  17. Progress Reports

  18. Exit Ticket • Tanika takes a 50°C glass of water (50g) and completely freezes it. How much energy did was released by the water? HOMEWORK: FINISH WORKSHEET 1, 2, and 3

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