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 (CaCl 2 (aq)) and sodium nitrate (NaNO 3 (aq)), you might be tempted to predict that the following chemical reaction would occur: CaCl 2 (aq) + 2NaNO 3 (aq)  Ca(NO 3 ) 2 (aq) + 2NaCl (aq) Net Ionic Equation

Dissociation occurs:

This means that what we really have in the beaker is: Ca 2+ (aq) + Cl − (aq) + Na + (aq) + NO 3 − (aq)  Ca 2+ (aq) + NO 3 − (aq) + Na + (aq) + Cl − (aq) Did a reaction occur? Detailed Ionic Equation

Now consider the reaction of aqueous silver nitrate with aqueous sodium carbonate: AgNO 3 (aq) + Na 2 CO 3 (aq)  Ag 2 CO 3 (s) + NaNO 3 (aq) What is different about this reaction? Detailed Ionic Equation

The detailed ionic equation would look like this: Ag + (aq) + NO 3 − (aq) + Na + (aq) + CO 3 2− (aq)  Ag 2 CO 3 (s) + Na + (aq) + NO 3 − (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) + CO 3 2− (aq)  Ag 2 CO 3 (s) The balanced net ionic equation would therefore be: 2 Ag + (aq) + CO 3 2− (aq)  Ag 2 CO 3 (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) + MgBr 2 (aq) → BaS(aq) + NiSO 4 (aq) → (NH 4 ) 2 SO 4 (aq) + ZnCl 2 (aq) → AlCl 3 (aq) + LiOH(aq) →