Classes of Chemical Reactions

1
Classes of Chemical Reactions

• Experiment 21

2
Classes of Reactions

• We will study several types of reactions
  including
• Precipitation reactions (aka replacement
  reactions)
• Acid-Base reactions
• Complexation reactions
• Oxidation-reduction reactions

3
Precipitation Reactions

• Sometimes two water soluble substances will form
  a substance that is insoluble in water.
• The insoluble substance is called a precipitate.
• Example
• AgNO3(aq) NaCl (aq) ? AgCl (s) NaNO3(aq)
• AgCl is insoluble in water.

4
Acid-Base Reactions

• The Bronsted-Lowry theory defines an acid as any
  species that provides hydrogen ions. An acid is
  often referred to as a proton donor.
• The Bronsted-Lowry theory defines a base as any
  species that receives hydrogen ions from an acid.
  Bases are often referred to as proton acceptors.

5
Neutralization Reactions

• A very important acid-base reaction is a
  neutralization reaction.
• An acid and a base will react to form a salt and
  water.
• Example
• HCl(aq) NaOH (aq) ? NaCl (aq) H2O (l)

6
Complexation Reactions

• Coordination Complex/Compound species formed
  when metal ions, usually transition metal ions,
  react with certain neutral molecules and
  negatively charged ions
• Ligand the neutral or anionic species which
  reacts with the metal ion
• A ligand must contain at least one pair of
  non-bonding valence electrons

7
Oxidation-Reduction Reactions

• Oxidation-reduction reactions are often referred
  to as redox reactions.
• These reactions involve the transfer of electrons
  from one species to another.
• Redox reactions are often split into
  half-reactions.

8
Redox Reaction

• An example of a redox reaction with its half
  reactions is given below.
• Cl2 2I- ?2Cl- I2
• Cl2 2e- ? 2Cl - reduction
• 2I - ? I2 2e- oxidation

9
Procedure Notes

• Use well plates instead of test tubes wherever
  possible.
• Skip the following sections
• Section B paragraph 3
• Section D parts 1, 3, 7
• Perform the following sections in the fume hood
• Section C part 1
• Section D part 4

10
Waste Disposal

• All silver nitrate, lead acetate, barium
  chloride, sodium thiocynate, 1,10-phenanthroline,
  potassium permanganate, nickel sulfate, acids,
  and bases need to be collected for proper
  disposal.
• Use a plastic pipet to transfer the waste in your
  well plates to the waste beakers.
• Make sure you know what chemicals you have in
  which well!!!!!!