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Chemical Reactions

Chemical Reactions. Ch.21 Sec.1. Chemical Reactions. Occurs with chemical changes Make new substances Change in which one or more substances are converted into new substances. Signs of Chemical Reactions. Change in color Release of light, heat, gas, sound, or smell.

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Chemical Reactions

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  1. Chemical Reactions Ch.21 Sec.1

  2. Chemical Reactions • Occurs with chemical changes • Make new substances • Change in which one or more substances are converted into new substances

  3. Signs of Chemical Reactions • Change in color • Release of light, heat, gas, sound, or smell

  4. Examples of Chemical Reactions • Growing • Ripening • Decaying • Burning • Rusting

  5. Law of Conservation of Mass • Mass cannot be created or destroyed • Chemical reactions rearrange atoms • Break bonds, rearrange, and make new bonds • Energy breaks bonds

  6. Chemical Equation • A way to describe a chemical reaction using chemical formulas and other symbols • Pg. 635; Table 1 and equation

  7. Products & Reactants • Reactants = left side of equation (ALWAYS) • Products = right side of equation (ALWAYS)

  8. Chemical Equations • Balanced chemical equation – has same number of atoms of each element on both sides of the equation • Satisfies the Law of Conservation of mass.

  9. Reaction Types • Synthesis • Decomposition • Single Displacement • Double Displacement • Combustion

  10. Synthesis • Combines 2 substances to make 1 compound • A + B --> AB • Blue + Red --> Purple • Na + Cl --> NaCl • 1 Product

  11. Synthesis

  12. Decomposition • Takes 1 compound and breaks it apart into 2 or more substances • AB --> A + B • H2O --> H2 + O2 • Opposite of synthesis • 1 Reactant

  13. Decomposition

  14. Single-Displacement • 1 element swaps places with another element that is in a compound • XA + B --> XB + A • B and A swapped places • ** Has 1 compound and 1 element on both sides • Ex: CuCl2 + Al --> AlCl3 + Cu

  15. Single-Displacement

  16. Double - Displacement • 2 compounds exchange elements with each other • AX + BY --> AY + BX • ** 2 Compounds on both sides • Ex: NaCl + AgF NaF + AgCl

  17. Double - Displacement

  18. Combustion • Oxygen and another compound BURN to make new products • Oxygen is ALWAYS a reactant • CO2 + H2O is ALWAYS a product • Ex: CH4 + O2 --> CO2 + H2O

  19. Double Displacement Decomposition Single Displacement Synthesis HCl + NaOH --> H2O + NaCl NaCl --> Na + Cl2 Al + Fe2O3 --> Al2O3 + Fe P4 + O2 --> P4O10 What Type of Reaction?

  20. 2 Types Energy Reactions • Endothermic • Exothermic

  21. Endothermic • Endo = in • Energy is taken in (absorbed) with reactants • Drops surrounding environment temp. • Ex: Photosynthesis - takes in sunlight

  22. Exothermic • Exo = out • Energy is released or given out with products • Raises surrounding environment’s temperature • Ex: hand warmers

  23. Exo or Endo? • Exo • Exo • Endo • Exo • Paper burning • Firecracker Exploding • Plant making its own food • Electric blanket

  24. Reaction Rate • How fast a reaction is going • Factors on rate: • Temperature • Surface Area • Concentration • Stirring • Catalysts

  25. Catalysts • Substance that speeds up reaction without being permanently changed • Ex: Enzymes in our stomach speed up digestion (lactose)

  26. Inhibitors • Substance used to slow down a chemical reaction • Ex: Food preservatives (prevent spoilage) • Product is not changed just how fast or slow the rate of production occurs

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