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REVIEW TIME!

REVIEW TIME!. What type of energy cooks food in a microwave oven? ELECTROMAGNETIC ENERGY What type of energy is the spinning plate inside of a microwave oven? MECHANICAL ENERGY. What type of Energy?. Kinetic + Potential! (Mechanical energy). QUIZ TIME!.

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REVIEW TIME!

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  1. REVIEWTIME! What type of energy cooks food in a microwave oven? ELECTROMAGNETIC ENERGY What type of energy is the spinning plate inside of a microwave oven? MECHANICAL ENERGY

  2. What type of Energy? Kinetic + Potential! (Mechanical energy)

  3. QUIZ TIME! Electrical energy is transported to your house through power lines. When you plug an electric fan to a power outlet, electrical energy is transform into what type of energy? MECHANICAL ENERGY

  4. QUIZ TIME! What energy transformation occurs when an electric lamp is turned on? ELECTRICAL ENERGY  ELECTROMAGNETIC ENERGY (Light energy)

  5. Energy Transfer Sound (mechanical) Electrical Thermal Mechanical Electrical Chemical Electrical Light (Electromagnetic)

  6. Do Now-YOU HAVE 10 minutes. Work Quickly! • Get with your group. • Complete your group worksheet. • Practice your presentation ATLEAST once. • Designate one person in your group to hold up the appropriate types of energy cards at the end of the presentation. Make this OSCAR-worthy!!

  7. And the Oscar goes to… • Take a piece of scrap paper and rip it into 3 parts • On one piece, nominate someone for BEST ACTOR • On another piece, nominate someone for BEST SUPPORTING ACTOR • On the last piece, nominate a BEST MOVIE (list the scenario you enjoyed seeing played out the best)

  8. Thermochemistry • The study of heat change in chemical reactions.

  9. Heat Change in Chemical Reactions • For a chemical reaction to occur, bonds must be both formed and broken Fe + CuSO4 Cu + FeSO4 • Energy is needed to break bonds. • Energy is released when bonds are formed.

  10. 2H2(g) + O2(g) 2H2O (l) + energy H2O (g) H2O (l) + energy energy + 2HgO (s) 2Hg (l) + O2(g) energy + H2O (s) H2O (l) Exothermic process is any process that gives off heat – transfers thermal energy from the system to the surroundings. Endothermic process is any process in which heat has to be supplied to the system from the surroundings. 6.2

  11. Thermochemical Equations • 4Fe (s) + 3O2 (g) 2Fe2O3 (s) + 1625 kJ • Does this reaction give off heat or absorb heat? • Exothermic or endothermic?

  12. Thermochemical Equations • C (s) + 2S (s) + 89.3 kJ  CS2 (l) • Is heat released or absorbed in this chemical reaction? • Exothermic or endothermic?

  13. Enthalpy (H) is used to measure the heat flow into or out of a system in a process that occurs at constant pressure. DH = H (products) – H (reactants) Hproducts < Hreactants Hproducts > Hreactants DH < 0 DH > 0 6.3

  14. Enthalpy(heat flow) is measured in: • Joules (J) • Kilojoules (kJ) • 1 kJ = 1000 Joules

  15. Energy Level Diagrams Endothermic reactions products energy energy taken in is positive, ∆H is positive reactants The products are higher in energy than the reactants time of reaction

  16. Energy Level Diagrams Exothermic reactions Energy given out is negative; ∆H is negative reactants energy products Time of reaction The products are lower in energy than the reactants

  17. Endothermic or Exothermic?

  18. Endothermic or Exothermic? What does DH equal? 80kJ-160kJ = -80kJ DH = H (products) – H (reactants)

  19. Endothermic or Exothermic? What does DH equal? DH = H (products) – H (reactants)

  20. Endothermic or Exothermic? What does DH equal? DH = H (products) – H (reactants)

  21. Endothermic or Exothermic? Exo! Endo! What does DH equal? DH = H (products) – H (reactants)

  22. Endothermic or Exothermic?

  23. Consider this reaction: • 2C2H6 + 7O2 → 4CO2 + 6H2O + 3120 kJ a. endothermic or exothermic? b. If 28 moles of oxygen are reacted, how much energy will be produced? exothermic 3,120 x 4 = 12, 480 kJ

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