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Catalyst

Catalyst. Update your learning target log and organize your binder. 4 th : Keep ET7.4 out on the table. HW 7.2 due. End. I. Latent Heat. Latent heat = energy released or absorbed during a phase change. 2. Equation: q = ±mΔH m = mass of object ΔH = ΔH fus or ΔH vap

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Catalyst

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  1. Catalyst • Update your learning target log and organize your binder. • 4th: Keep ET7.4 out on the table. HW 7.2 due End

  2. I. Latent Heat • Latent heat = energy released or absorbed during a phase change. 2. Equation: q = ±mΔH • m = mass of object • ΔH = ΔHfus or ΔHvap 3. Exothermic: q = -mΔH Endothermic: q = +mΔH

  3. Putting it All Together Melting ice q1 = mΔHfus Heating water q2 = mcΔT qTOTAL= q1 + q2 = mΔHfus + mcΔT

  4. Example (I Do): What is the energy required to melt 100g of ice at 0˚C and heat it to a temperature of 100 ˚C? (c = 4.2 J/g˚C; ΔHfus = 334 J/g

  5. Example (We Do): What is the energy released 200 g of water vapor at 100 ˚C condenses and then cools to 50 ˚C? (c = 4.2 J/g˚C; ΔHvap = 2260 J/g)

  6. Whiteboard Question #1 How much heat energy is required to melt 200 g of ice (latent heat of fusion = 334 J/g)

  7. Whiteboard Question #2 How much energy is released when 200 g of water cools from 50 ˚C to 40 ˚C? (specific heat = 4.2 J/g˚C) - What is the value of q?

  8. Whiteboard Question #3 How much energy in kJ is required to heat 150 g of water at 40 ˚C to 100 ˚C and boil all of the water? (specific heat = 4.2 J/g ˚C; latent heat of vaporization = 2260 J/g)

  9. Calculate the amount of heat energy required to melt all of the ice. The latent heat of fusion of ice is 334 J/g.

  10. Suppose that all of the ice melts into water by midday. Calculate the amount of heat energy supplied by the sun to raise the temperature of the water from 0 ˚C to 22 ˚C. The specific heat of ice is 2.1 J/g˚C.

  11. C-O-N-N-E-C-T 4 • Place the following answers in your grid in any order you choose: • 3006 J, 62,779 J, 418.14 J, Exothermic, 376.7 kJ, 2.179 kJ, 20,340 J, 51,980 J, 370.8 J, Endothermic, -41,000 J, 961, 400 J, 7682 J, 668,000 J, 3762 J, 6780 kJ

  12. C-O-N-N-E-C-T 4 • A reaction that requires energy to proceed. • Calculate the energy required to melt 2000 g of ice at 0 ˚C. • Calculate the energy required to boil 3 kg of water at 100 ˚C. • 23.0 g of ice is at a temperature of -46.0 ˚C. How many joules of energy are necessary to heat the ice to 0 ˚C? • How much energy is required to raise the temperature of 1000 g of water from 10 ˚C to 100 ˚C? • Calculate the energy needed to change 9 g of ice at 0 ˚C to liquid water at 0 ˚C. • An ice cube tray contains 0.45 kg of water at 22 ˚C. How much heat must be removed to cool the water to 0 ˚C? • How much energy is required to heat 25.0 g of water from 40 ˚C to 100 ˚C and boil all the water?

  13. Closing Time • Homework: - Study! • Unit 7 Test Thurs./Fri. • Unit 6 Test = zero in the gradebook if you have not taken it yet.

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