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O.A # 37

O.A # 37. Questions 39, 40, 41, 42, 43. Chapter 16. Energy and Chemical Change. Page # 22- Measuring Heat. Calorie: Calorie is defined as the amount of heat required to raise the temperature of one gram of pure water by one degree Celsius. 1 C alorie = 1 Kilocalorie = 1000 c alories

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O.A # 37

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  1. O.A # 37 Questions 39, 40, 41, 42, 43

  2. Chapter 16 Energy and Chemical Change

  3. Page # 22- Measuring Heat Calorie: Calorie is defined as the amount of heat required to raise the temperature of one gram of pure water by one degree Celsius. 1 Calorie = 1 Kilocalorie = 1000 calories Joule: Joule is the SI unit of heat and energy

  4. a. 1calorie = _______ Joules b. 1kj = _______Joules c. 1kcal = 1Cal = ________ calories 4.184 1000 1000 Practice Problems on Page 492 (#1-3) 1) A fruit and oatmeal bar contains 142 nutritional Calories. Convert this energy to calories. x 1000 cal = 1 Cal 142000 calories 142 Calories

  5. a. 1 calorie = 4.184 Joules b. 1kj = 1000 Joules c. 1kcal = 1 Cal = 1000 calories 2) An exothermic reaction releases 86.5 kJ. How many kilocalories of energy are released? 86.5 kJ x 1 kcal 4.184 kJ = 20.7 kcal 3) If an endothermic reaction process absorbs 256 J, how many kilocalories are absorbed? = 0.0612 kcal x 1 cal 4.184 J = 61.2 cal x 1 kcal 1000 cal 256 J

  6. Page # 23- Energy • Energy is the ability to do work or to produce heat. 2 basic types of Energy • Potential energy: energy stored • Kinetic energy: energy of motion Law of Conservation of Energy. • The Law of Conservation of Energy states that in any chemical reaction or physical process, energy can be converted from one form to another, but is neither created nor destroyed.

  7. Heat Heat is energy that is in the process of flowing from a warmer object to a cooler object Heat released (-) = Heat Absorbed (+) • q = c .m . ∆T • q= heat released or absorbed (Joules, J) • m = mass (g) • ∆T = temperature change = Tfinal – Tinitial • C = specific heat capacity: • Is the amount of heat required to raise the temperature of any substance by one degree Celsius CH2O = 4.18 J/gºC Cice = 2.03 J/gºC Summary:

  8. O.A # 107 Questions 33,34,35,36,37

  9. Page # 22 Heat in Chemical Reactions Thermochemistry Is the study of heat changes that accompany chemical reactions and phase changes. Products Endothermic Reactions: • P > R • Heat is absorbed • Temperature increases • Melting (solid-liquid) • Boiling (liquid-gas) q Energy Reactants time

  10. time Exothermic Reactions: • R > P • Heat is released • Temperature decreases • Freezing (liquid-solid) • condensing (gas-liquid) Reactants q Energy Products time

  11. Write the following equations using E to represent the energy involved. • Solid copper melting • Water vapor condensing • HCl boiling • Water freezing Cu(S)+ ECu(L) Endothermic reaction: + E Exothermic reaction: E + H2O(G) H2O(L) + E HCl(L) + EHCl(G) H2O(L)  H2O(S) + E

  12. Enthalpy of Reaction Enthalpy (H) is the heat content of a system at constant pressure Equation ∆H = H final - H initial ∆H = Hproducts - Hreactants ∆H (-): exothermic ∆H (+ ): endothermic Summary:

  13. O.A # 108 Questions 9,10,11,12,13

  14. Page # 23- Heat in Phase Changes Heat of Fusion (Hf) • Heat required to melt one mole of a substance at its melting point • q = Hf x moles Heat of Vaporization (Hv) • Heat required to vaporize one mole of a substance at its boiling point • q = Hv x moles

  15. If the Hf of water is 6.01 KJ/mole, and Hv is 40.7 KJ/mole, how much energy is required to melt 45.23 g of ice? q = Hf x moles 45.23 g x 1 mole 18.0 g = 2.513 moles q = 6.01 KJ/mole x 2.513 moles q = 15.1 KJ

  16. How much heat is required to boil 30.5 grams of water? q = Hv x moles 30.5 g x 1 mole 18.0 g = 1.69 moles q = 40.7 KJ/mole x 1.69 moles q = 68.8 KJ Summary:

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