SCH4U - Net Ionic Equations - III

Recall the solubility rules

• Any compound with K (potassium) is soluble, thus its aqueous (aq)

• Most hydroxides are insoluble - unless attached to K (potassium), Na (sodium), or NH4+ (the ammonium polyatomic ion), thus they would be solid (s)

What are the 3 stages required to write the Net Ionic Equation?

1. Write the Balanced Chemical Equation

2. Write the Total Ionic Equation

3. Write the Net Ionic Equation

Note: if you are already given total ionic equation, of course you are not going to restart by writing the balanced chemical equation.

How do you go from a balanced chemical equation to a total ionic equation?

• Any chemical entity in aqueous form must be rewritten in ion form (complete with aqueous state); in other words, you are splitting aqueous chemical entities into their constituent ions, including their charge and aqueous state.

How do you go from a total ionic equation to a net ionic equation?

• Cancel all “spectator ions” - ions which have not changed in regards to their charge or state from one side of the reaction to the other side.

Define “spectator ions”

• These are ions within a chemical equation which do not change from one side to the other - in other words, THEY do not participate in the chemical reaction, they are simply “spectating”

Why do we care so much about writng the balanced chemical equation, total ionic equation and net ionic equation in regards to this unit?

• Writing these 3 correctly directly carries us into writing proper redox reactions, writing proper balanced half - reactions, or assigning oxidation numbers easily in order to determine oxidation and reduction reactions.