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Agenda:

Agenda:. Warm-up: Word Equations Chemical reactions and energy Endothermic or exothermic How energy is represented in chemical reactions Practice: Predicting products Using types of reactions Cards. Homework :. #13 Zinc II hydroxide + hydrochloric acid Zinc II chloride + water

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Agenda:

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  1. Agenda: Warm-up: Word Equations Chemical reactions and energy Endothermic or exothermic How energy is represented in chemical reactions Practice: Predicting products Using types of reactions Cards • Homework:

  2. #13 Zinc II hydroxide + hydrochloric acid Zinc II chloride + water #17 Sodium carbonate + sulfuric acid Sodium sulfate + water + carbon dioxide Word Equations: Hand-inWrite the formulas and balance

  3. Representing the energy changes in reactions Thermo-chemistry Energy in Reactions

  4. Representing energy in chemical reactions 1. Measurement of energy: joules Joules/gram or joules/mole 2. Energy shown as a reactant or product Endothermic: Exothermic: 3. Change in energy: ∆H (heat of reaction) Positive + ∆ Negative -∆ 4. Diagrams of the energy

  5. Energy in reactions Exothermic reactions • Energy is given out • The products have less energy than the reactants Exothermic reactions are common. Combustion and neutralization (a special type of double replacement reactions) are exothermic

  6. Energy Level Diagrams Exothermic reactions energy

  7. Energy Level Diagrams Exothermic reactions energy course of reaction

  8. Energy Level Diagrams Exothermic reactions energy reactants course of reaction

  9. Energy Level Diagrams Exothermic reactions energy reactants products course of reaction

  10. Energy Level Diagrams Exothermic reactions energy given out ∆H is negative energy reactants products course of reaction

  11. Energy Level Diagrams Endothermic reactions • Energy is taken in • The products have more energy than the reactants The energy is taken in from the surroundings

  12. Energy Level Diagrams Endothermic reactions energy

  13. Energy Level Diagrams Endothermic reactions energy course of reaction

  14. Energy Level Diagrams Endothermic reactions energy reactants course of reaction

  15. Energy Level Diagrams Endothermic reactions energy products reactants course of reaction

  16. Energy Level Diagrams Endothermic reactions energy products energy taken in ∆H is positive reactants course of reaction

  17. Summary Table

  18. Summary Table

  19. Summary Table

  20. Summary Table

  21. ∆H = Enthalpy =Change in Energy How much energy is given out or taken in? • Energy is needed to break chemical bonds • Energy is given out when bonds are made ∆H is the differencebetween the energy needed to break the bonds in the reactants, and the energy given out when new bonds are made in the products

  22. Working out ∆H Summary • The energy values have units of kJ/mole • Energy goes in to break bonds • Energy goes out when bonds are made ∆H is difference between energy in – energy out

  23. Practice: Reactions Determine types of reactions Determine if the reaction is endothermic or exothermic

  24. Energy

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