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**Thermal Energy Transfer**

D2.3 Thermal Energy Transfer in the Hydrosphere

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Thermal energy is transferred through the hydrosphere from warmer latitudes to cooler polar regions largely due to global winds.

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**Specific Heat Capacity**

The specific heat capacity is the amount of heat energy needed to raise the temperature of one gram of a substance by one degree celcius. The specific heat capacity of water is extremely large when compare to most other substances! Sweet. Napoleon sez:

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**Quantity of Thermal Energy**

This is the amount of thermal energy that is released or absorbed by one gram of a substance when its temperature changes by one degree celcius. Q = thermal energy ( J ) m = mass ( g ) c = specific heat capacity ( J/g ºC ) Δt = change in temperature ( ºC ) A simple foam cup calorimeter.

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examples: 1) A 350-g mass of water at 12.0ºC is allowed to warm up to 30.0ºC. Determine the amount of thermal energy, Q, absorbed. The theoretical specific heat capacity of water is 4.19 J/gºC. 2.64 x 104 J 2) Determine the quantity of energy required to warm a 2.00-kg block of ice from ºC to -10.0ºC. The theoretical specific heat capacity of ice is 2.00 J/gºC. Express your answer in kilojoules. 60.0 kJ

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examples: 3) Calculate the change in temperature, Δt, that occurs when 30.0 kJ of thermal energy is added to 2.00 kg of copper. The theoretical specific heat capacity of copper is J/gºC. 39.0ºC 4) When 680 J of thermal energy is added to 30.0 g of iron, the temperature of the iron increases by 51.1ºC. What is the experimental specific heat capacity of iron? 0.444 J/gºC

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Homework: read pages 376 – 380 pages 379 – 380, Practice Problems #’s 1 – 8 1) × 104 J 5) 20 ºC 2) × 104 J 6) water: 0.119ºC iron: 1.11ºC 3) × 103 J 7) J/gºC 4) × 104 J 8) J/gºC

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(see text page 382)

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**During a phase change, the temperature of water remains constant.**

(text page 385) During a phase change, the temperature of water remains constant.

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Heat of Fusion The heat of fusion of a substance is the amount of energy released or absorbed when it changes from a liquid to a solid, or from a solid to a liquid. fusion solidification Hfus = heat of fusion ( kJ/mol ) Q = thermal energy ( kJ ) n = number of moles of substance ( mol ) mass ( g ) molar mass ( g/mol )

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Heat of Vaporization The heat of vaporization of a substance is the amount of energy released or absorbed when it changes from a gas to a liquid, or from a liquid to a gas. vaporization condensation Hvap = heat of vaporization ( kJ/mol ) Q = thermal energy ( kJ ) n = number of moles of substance ( mol )

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examples: 1) When 4.18 kJ of thermal energy is added to 12.5 g of ice at its melting point, the ice changes phase. Given the molar mass of water is g/mol, calculate the experimental heat of fusion of ice. 6.03 kJ/mol 2) Calculate how much thermal energy is required to completely vaporize 30.0 g of liquid water, given that water has a molar mass of g/mol and the heat of vaporization of water is kJ/mol. 67.7 kJ

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examples: 3) Determine the number of moles of silver at its melting point that can be melted by the addition of 50.0 kJ of energy, given that the heat of fusion of silver is kJ/mol. 4.46 mol

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Homework: read pages 382 – 389 pages 386 – 387, Practice Problems #’s 9 – 15 D2.3 Check and Reflect page 390 #’s 1 – 2, 4, 6 – 8, 11 – 23 9) kJ/mol 13) kJ/mol 10) kJ 14) kJ/mol 11) mol 15) × 103 kJ 12) kJ/mol

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