Chemistry Notes
Chapter 11.
CHEMICAL REACTIONS
Addresses part of Massachusetts Curriculum Frameworks, content standard 5

•   Evidence of a chemical reaction
•   Writing chemical reactions (s) = solid (l) = liquid (g) = gas (aq) = aqueous solution
•   Balancing chemical reactions H₂O NH₃

  Make sure all formulas are correct!     You may not change them! Remember 7 elements that form diatomic molecules: H2, N2, O2,   F2, Cl2, Br2, I2 Uncombined elements should be balanced LAST Keep polyatomic ions together as much as possible If OH- occurs, rewrite water as HOH Proceed by trial and error, one thing at a time When finished, check everything over again

•   Types of chemical reactions
  • Synthesis   (usually includes oxidation/reduction)
  • Decomposition   (usually includes oxidation/reduction)
  • Combustion of a compound = decomposition + synthesis   (always includes oxidation/reduction)
  • Single replacement   (always includes oxidation/reduction)
  • Double replacement (double displacement, metathesis)
•   Predicting oxidation-reduction reactions;   activity series

  Loss of Electrons is Oxidation - - L. E. O. Gain of Electrons is Reduction - - G. E. R. Remember:   LEO says "GER" LEO

•   Types of double replacement reactions:
  • Reversible equilibria
  • Reactions that form water (acid/base neutralizations, etc.)
  • Precipitation reactions Solubility rules
  • Reactions that produce gases

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