Sunday, May 15, 2011

Final Exam Review #17

How do you know if a double replacement reaction will occur?

  • a solid (precipitate) or gas must form (according to the solubility rules)
    1. All common compounds of Group I and ammonium ions are soluble.
    2. All nitrates, acetates, and chlorates are soluble.
    3. All binary compounds of the halogens (other than F) with metals are soluble, except those of Ag, Hg(I), and Pb. Pb halides are soluble in hot water.)
    4. All sulfates are soluble, except those of barium, strontium, calcium, lead, silver, and mercury (I). The latter three are slightly soluble.
    5. Except for rule 1, carbonates, hydroxides, oxides, silicates, and phosphates are insoluble.
    6. Sulfides are insoluble except for calcium, barium, strontium, magnesium, sodium, potassium, and (ammonium
  • it also occurs if an acid and a base create a salt and water
  • Example:  In the chemical equation below, according to the solubility rules the product copper (II) hydroxide is a solid and sodium nitrate is aqueous, therefore the double replacement reaction occurs.

    How do you know if a single replacement reaction will occur?
    • the single metal must be more reactive than the metal or non-metal in a compound
    • Use the activity series to see if element one is higher than element two in order for the reaction to occur, if not the reaction does not occur
    • Example: In the chemical equation below chlorine replaces bromine. Chlorine is higher than bromine on the activity series so the single replacement will take place.


    Explain the process of using oxidation numbers to predict the product of a reaction.

    • oxidation numbers are used to find the number of the nonmetal "cations" to determine the polyatomic ion in the acid
    • it is not a real cation because cations are metals, but when I am referring to "cation" it is because we are looking for the negative charge of S which is a nonmetal

    If you have the equation SO2 +H20, in order to write the product of this combination you need to know the number of "cation" of S in the SO2.

    x= number of "cations" of the S (sulfur) which in this equation = 4
    The first two represents that there are two oxygens.  The -2 represents the charge of oxygen.  Lastly, the 0 represents the charge of the polyatomic ion which is nothing.

    Now use the same setup of an equation with sulfite and sulfate to see which has the same number of "cations" as SO2.  We use sulfite and sulfate because we know their "cations".

    Since SO2 and sulfite both have 4 as the number of "cations" of S, the balanced equation of the combination would look like: