Reactions

• Ionic solutions can be identified by their ability to conduct electricity.

• If a large number of ions are present in a solution, the solution will be an excellent conductor of electricity.

• Such a substance is completely ionized and is a strong electrolyte. All soluble ionic compounds, but very few molecular compounds are strong electrolytes.

• Electrolytes, non-electrolytes and weak electrolytes

• If the solution conducts electricity only weakly, there is likely to be only a few ions present. Such a substance is partially ionized and is a weak electrolyte.

• Non-electrolytes have no ions present in solution and therefore cannot conduct electricity.

• Such a substance is NOT ionized and is a non-electrolyte. Most molecular compounds are either nonelectrolytes or weak electrolytes

• Electrolytes, non-electrolytes and weak electrolytes

• Net ionic equation: a chemical equation that shows only ions or pure substances that are changed in the reaction

• Spectator ion: an ion that remains in solution and does not participate in a chemical reaction

Net Ionic Equation

• If you mixed aqueous solutions of calcium chloride (CaCl2 (aq)) and sodium nitrate (NaNO3 (aq)), you might be tempted to predict that the following chemical reaction would occur:

CaCl2 (aq) + 2NaNO3 (aq) Ca(NO3)2 (aq) + 2NaCl (aq)

Net Ionic Equation

Dissociation occurs:

• This means that what we really have in the beaker is:

Ca2+ (aq) + Cl− (aq) + Na+ (aq) + NO3− (aq)

Ca2+ (aq) + NO3− (aq) + Na+ (aq) + Cl− (aq)

• Did a reaction occur?

Detailed Ionic Equation

• Now consider the reaction of aqueous silver nitrate with aqueous sodium carbonate:

• AgNO3 (aq) + Na2CO3 (aq) Ag2CO3 (s) + NaNO3 (aq)

• What is different about this reaction?

Detailed Ionic Equation

• The detailed ionic equation would look like this:

• Ag+ (aq) + NO3− (aq) + Na+ (aq) + CO3

2− (aq) Ag2CO3 (s) + Na+ (aq) + NO3

− (aq)

• If we cancel out the spectator ions…

• What would be left?

Detailed Ionic Equation

• we are left with the unbalanced net ionic equation for this reaction:

Ag+ (aq) + CO32− (aq) Ag2CO3 (s)

• The balanced net ionic equation would therefore be:

2 Ag+ (aq) + CO32− (aq) Ag2CO3 (s)

Net Ionic Equation

• Strong acids and bases are written in ionic form; weak acids and bases are written in molecular form

• Polyprotic Acids: The second and subsequent ionizations are always weak, whether or not the original is strong or weak.

• Soluble Salts are written in ionic form• Insoluble Salts are written in the molecular form • Solids, liquids and gases are always written in

molecular form.

Solubility Rules

Predict if a reaction takes place between the following solutions. If it does, write a net ionic equation for the reaction.•KOH(aq) + MgBr2(aq) →

•BaS(aq) + NiSO4(aq) →

•(NH4)2SO4(aq) + ZnCl2(aq) →

•AlCl3(aq) + LiOH(aq) →