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Reaction Energy and Reaction Kinetics

Reaction Energy and Reaction Kinetics. Chapter 17 Notes. Units for Heat. calorie (cal) = the amount of heat needed to raise the temperature of 1 gram of water by 1 o C. The “c” is ALWAYS lowercase for this unit.

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Reaction Energy and Reaction Kinetics

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  1. Reaction Energy and Reaction Kinetics Chapter 17 Notes

  2. Units for Heat • calorie (cal) = the amount of heat needed to raise the temperature of 1 gram of water by 1oC. The “c” is ALWAYS lowercase for this unit. • Calorie (Cal) = 1 kilocalorie (kcal). This is what we mean when we talk about food – how much energy is in the food. The “C” is ALWAYS capitalized! • Joule = SI unit for energy, including heat

  3. Heat Capacity • The amount of heat needed to change an object’s temperature. • This depends on • Size of the object • Material of the object • How big is the temperature change • To allow more direct comparisons we use specific heat capacity instead.

  4. Specific Heat Capacity • The amount of heat need to change the temperature of 1 gram of a material by 1oC • For water, c = 4.18 J/g∙oC • This means it takes 4.18 joules of energy to raise the temperature of 1 gram of water from 20oC to 21oC • You have been given a table of specific heats. This needs to go in the references section of your binder.

  5. Calculating Specific Heat Heat (J or cal) Specific heat (J/g∙oC or cal/g∙oC) Change in temperature = Tfinal – Tinitial (oC or K) Mass (g)

  6. Example 1 • The temperature of a piece of copper with a mass of 95.4 grams increases from 25.0oC to 48.0oC when the metal absorbs 849 J of heat. What is the specific heat of copper?

  7. Example 1 • The temperature of a piece of copper with a mass of 95.4 grams increases from 25.0oC to 48.0oC when the metal absorbs 849 J of heat. What is the specific heat of copper?

  8. Example 1 • The temperature of a piece of copper with a mass of 95.4 grams increases from 25.0oC to 48.0oC when the metal absorbs 849 J of heat. What is the specific heat of copper?

  9. Example 2 • How much heat is required to raise the temperature of 250.0 g of mercury 52.0oC?

  10. Example 2 • How much heat is required to raise the temperature of 250.0 g of mercury 52.0oC?

  11. Example 2 • How much heat is required to raise the temperature of 250.0 g of mercury 52.0oC?

  12. Example 3 • What is the temperature change when 2543 J of heat are added to 76.4 g of alcohol?

  13. Example 3 • What is the temperature change when 2543 J of heat are added to 76.4 g of alcohol?

  14. Example 3 • What is the temperature change when 2543 J of heat are added to 76.4 g of alcohol?

  15. Example 4 • The temperature of a 283 gram sample increases 11.2oC by absorbing 1204 J of heat. What material is the sample?

  16. Example 4 • The temperature of a 283 gram sample increases 11.2oC by absorbing 1204 J of heat. What material is the sample?

  17. Example 4 • The temperature of a 283 gram sample increases 11.2oC by absorbing 1204 J of heat. What material is the sample?

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