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Thermodynamics

Thermodynamics. Unit 10. Quantitative Measure of Energy in Phase Changes. Heat of Fusion – amount of energy needed to melt 1 gram of a solid at its melting point Solid + E Liquid For water: 80.0 cal = Latent Heat 1 gram. melt (absorb E). freeze

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Thermodynamics

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  1. Thermodynamics Unit 10

  2. Quantitative Measure of Energy in Phase Changes Heat of Fusion – amount of energy needed to melt 1 gram of a solid at its melting point Solid + E Liquid For water: 80.0 cal = Latent Heat 1 gram melt (absorb E) freeze (release E) Free Template from www.brainybetty.com

  3. Quantitative Measure of Energy in Phase Changes Heat of Vaporization – amount of energy needed to vaporize 1 gram of a liquid at its boiling point Liquid + Energy Vapor For water: 539 cal = Latent Heat 1 gram vaporize (absorb E) condense (release E) Free Template from www.brainybetty.com

  4. Quantitative Measure of Energy in Phase Changes **These are for phase changes. (Remember, during a phase change, there is no change in T.) For a change in T, use Q = mcDT. Free Template from www.brainybetty.com

  5. Quantitative Measure of Energy in Phase Changes Examples: How many calories are absorbed or released when 20.0 g of ice is melted at 0.00oC? s  l Latent Heat of Fusion = 80.0 cal/g m = 20.0 g Free Template from www.brainybetty.com

  6. Quantitative Measure of Energy in Phase Changes 80.0 cal 20.0 g = 1600 cal 1 g 1.60 x 103 cal absorbed Free Template from www.brainybetty.com

  7. Quantitative Measure of Energy in Phase Changes How many calories are absorbed or released when 15.0 g of water vapor condenses at 100.0oC? g  l Latent Heat of Vaporization = 539 cal/g m = 15.0 g Free Template from www.brainybetty.com

  8. Quantitative Measure of Energy in Phase Changes 539 cal 15.0 g = 8085 cal 1 g 8090 cal released Free Template from www.brainybetty.com

  9. Quantitative Measure of Energy in Phase Changes How many calories are absorbed or released to raise 30.0 g of water from 25.0oC to 75.0oC? No phase change! q = mcDT q = ? m = 30.0 g c = 1.00 cal/goC Ti = 25.0oC Tf = 75.0oC Tf – Ti = 50.0oC Free Template from www.brainybetty.com

  10. Quantitative Measure of Energy in Phase Changes q = mcDT q = (30.0 g)(1.00 cal/goC)(75.0oC – 25.0oC) q = (30.0)(1.00)(50.0) q = 1500 cal q = 1.50 x 103 cal absorbed Free Template from www.brainybetty.com

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