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Thermochemistry

Thermochemistry. Do Now – Check and edit prelabs Objective – Thermochemistry Exothermic, endothermic, calorie, joule, heat capacity, and specific heat Homework – Pg 510 # 9-11. Energy Transformations. Energy is the capacity to do work or supply heat Energy has no mass or volume.

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Thermochemistry

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  1. Thermochemistry

  2. Do Now – Check and edit prelabs • Objective – Thermochemistry • Exothermic, endothermic, calorie, joule, heat capacity, and specific heat • Homework – Pg 510 # 9-11

  3. Energy Transformations Energy is the capacity to do work or supply heat Energy has no mass or volume

  4. Energy Transformations Energy is the capacity to do work or supply heat Energy has no mass or volume Thermochemistry = study of energy changes that occur during chemical reactions Heat (q) always flow from warmer to cooler

  5. Exothermic and Endothermic Processes System and Surroundings Law of conservation of energy

  6. Exothermic and Endothermic Processes System and Surroundings Law of conservation of energy

  7. Exothermic and Endothermic Processes Endothermic Reactions – System absorbs energy from surroundings Exothermic Reactions- System gives off energy to the surroundings

  8. Units of Measuring Heat Flow calorie = amount of heat it takes to raise the temp of 1 g of water 1 °C

  9. Units of Measuring Heat Flow calorie = amount of heat it takes to raise the temp of 1 g of water 1 °C 1 Calorie = 1 Kilocalorie = 1000 calories

  10. Units of Measuring Heat Flow calorie = amount of heat it takes to raise the temp of 1 g of water 1 °C 1 Calorie = 1 Kilocalorie = 1000 calories Joule (J) is the SI unit for measuring energy 1 J = 0.2390 cal 4.184 J = 1 cal

  11. Heat Capacity and Specific Heat (C) Heat Capacity = amount of heat needed to increase the temp of an object 1 °C

  12. Heat Capacity and Specific Heat (C) Heat Capacity = amount of heat needed to increase the temp of an object 1 °C Specific Heat = amount of heat needed to increase the temp of 1 gram of a material 1 °C

  13. Heat Capacity and Specific Heat (C) C =q= heat (Joules or calories)__ m x ∆T mass(g) x change in temp (°C )

  14. Calculating the Specific Heat of a Metal C =q= heat (Joules or calories)__ m x ∆T mass(g) x change in temp (°C ) Sample Problem 17.1 pg 510 The temperature of a 95.4 gram piece of copper increases from 25.0 °C to 48.0 °C when the copper absorbs 849 J of heat. What is the specific heat of copper?

  15. Calculating the Specific Heat of a Metal C =q= heat (Joules or calories)__ m x ∆T mass(g) x change in temp (°C ) Sample Problem 17.1 pg 510 The temperature of a 95.4 gram piece of copper increases from 25.0 °C to 48.0 °C when the copper absorbs 849 J of heat. What is the specific heat of copper?

  16. Enthalpy

  17. Enthalpy Heat content of a system at constant pressure

  18. Enthalpy qsys= ∆H = -qsurr = -m x C X ∆T

  19. 17.1 • 1.76 x 103cal 1.76 kcal 7.36 x 103 J 7.36 kJ • 2.36 x 10-1 J/(g*°C) 11. 2.8 x 102 kJ

  20. 17.2 18. 2Mg(s) + O2(g) → 2MgO(s) + 1204 kJ or 2Mg(s) + O2(g) → 2MgO(s) ∆H= -1204 kJ • 3.72 x 102 kJ 20. Heat of combustion is the heat of reaction for the complete burning of one mole of a substance.

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