Chemistry 2

Types of Reactions

  1. Reactions can placed in broad categories.
    1. Synthesis
      1. This occurs when the number of products is fewer than the number of reactants.
      2. In symbolic form: A + B --> AB
      3. An example of this is the formation of water: 2 H2(g) + O2(g) --> 2 H2O(l)
    2. Decomposition
      1. This occurs when the number of products is more than the number of reactants.
      2. In symbolic form: AB --> A + B
      3. Concrete example: 2 H2O(l) --> 2 H2(g) + O2(g)
    3. Single Replacement (or Displacement)
      1. This occurs when one element replaces another element in a compound.
      2. In symbolic form: A + BC --> AC + B or A + BC --> BA + C
      3. Concrete example: Zn(s) + CuSO4(aq) -> ZnSO4(aq) + Cu(s)
    4. Double Replacement (or Displacement)
      1. This occurs when two sets of elements switch places in a reaction.
      2. In symbolic form: AB + CD --> AD + CB
      3. Concrete example: 2 NaCl(aq) + Pb(NO3)2(aq) -->2 NaNO3(aq) + PbCl2(s)
      4. When the reaction is between an acid and a base (any compound that forms hydroxide ions), water is formed as one of the products. This is called Neutralization. For example:
        H2SO4(aq) + 2 NaOH(aq) --> 2 H2O(l) + Na2SO4(aq)
    5. Combustion
      1. Typically combustion occurs when a hydrocarbon reacts with oxygen to produce carbon dioxide and water. Hydrocarbons are a class of compounds that primarily consist of hydrogen and carbon.
      2. In symbolic form: CxHy + O2 --> CO2 + H2O
      3. Concrete example: 2 C2H6 + 7 O2 --> 4 CO2 + 6 H2O
  2. Some common chemical reactions that you should be familiar with:
    1. acid + base ----> water + ionic compound
    2. metal + oxygen ---> ionic compound
    3. metal + acid ---> hydrogen gas + ionic compound
    4. ionic compound1 + ionic compound2 ---> ionic compound3 + ionic compound4
    5. acid + carbonate ---> carbon dioxide + water + ionic compound
    6. metal1 + ionic compound1 ---> metal2 + ionic compound2
    7. hydrocarbon + oxygen ---> carbon dioxide + water