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Chemical Reactions

Chemical Reactions. Energy and Reaction Rates. Chemical Reactions. Chemical reactions require energy to start Activation E nergy - Energy needed to start a chemical reaction Endothermic reactions take in energy Exothermic reactions give off energy. Chemical Reactions. Chemical Reactions.

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Chemical Reactions

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  1. Chemical Reactions Energy and Reaction Rates

  2. Chemical Reactions Chemical reactions require energy to start Activation Energy - Energy needed to start a chemical reaction Endothermic reactions take in energy Exothermic reactions give off energy

  3. Chemical Reactions

  4. Chemical Reactions Activation Energy is represented by the top of the “hump” (Ea)

  5. Chemical Reactions A catalyst is something that speeds up a chemical reaction by lowering the activation energy An enzyme is a biological catalyst

  6. Chemical Reactions Activation Energy is lowered when a catalyst is present

  7. Chemical Reactions Reversible Reaction – synthesis reactions that can be reversed to become decomposition reactions Spectator Ions – Ions that remain aqueous throughout the chemical reaction Net Ionic Equation – Substances that remain after the spectator ions have been removed.

  8. Reaction Rates Reaction Rates – the time it takes for a chemical reaction to occur

  9. Reaction Rates • 4 Factors impact Reaction Rates 1. Concentration – the amount of material in a given amount of material

  10. Concentration

  11. Reaction Rates • 4 Factors impact Reaction Rates 2. Temperature – the measure of the average kinetic energy of molecules in a substance

  12. Reaction Rates • 4 Factors impact Reaction Rates • Surface Area Length x Width of all sides added together in a cube

  13. Reaction Rates

  14. Reaction Rates What is the surface area of the cube?

  15. Reaction Rates What is the surface area of the cube? 600 cm2

  16. Reaction Rates

  17. Reaction Rates 1000 small cubes. What is the surface area?

  18. Reaction Rates How many small cubes? What is the surface area of 1 small cube?

  19. Reaction Rates How many small cubes? What is the surface area of 1 small cube?

  20. Reaction Rates Surface area = 600 cm2 Surface area = 10 cm 6 cm2

  21. Reaction Rates Surface area = 600 cm2 Surface area = 10 cm 6 cm2 x 1000 = 6000 cm2

  22. Reaction Rates Which would dissolve faster ? Surface area = 600 cm2 Surface area = 6 cm2 x 1000 = 6000 cm2

  23. Reaction Rates • 4 Factors impact Reaction Rates 4. Catalyst Speeds up chemical reaction by lowering the activation energy (does not get used up!!)

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