1. Unit 4: Chemical Equations and Stoichiometry
Net Ionic Equations

2. Net Ionic Equations
For reactions taking place in water many substances dissociate (break apart) into ions
To write a net ionic equation you must determine which compounds dissociate and which do not

3. Net Ionic Rules Which molecules dissociate (break apart)???
Rule 1 – Solids, liquids, and gases
Do NOT dissociate
Rule 2 – Acids:
Strong acids dissociate: HCl, HBr, HI, H2SO4, HNO3, HClO4
Weak acids stay together
Rule 3 – Bases:
Strong bases dissociate: Group 1 and 2 hydroxides: LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Sr(OH)2, Ba(OH)2 – except Be(OH)2
Weak bases stay together

4. Net Ionic Rules Which molecules dissociate (break apart)???
Rule 4 – Ionic Compounds:
If soluble: dissociate
If insoluble: stay together
**Use the table on p. 125 in your textbook or the chart on your periodic table

5. Net Ionic Practice H2SO4 FeS KOH Ca(NO3)2 Cu3(PO4)2
Determine whether the following compounds dissociate in water or not:
H2SO4
FeS
KOH
Ca(NO3)2
Cu3(PO4)2

6. Net Ionic Equations
For reactions taking place in water many substances dissociate (break apart) into ions
To write a net ionic equation you must determine which compounds dissociate and which do not
Spectator ions: ions that do not actually participate in the reaction

7. Steps to Writing Net Ionic Equations
Example: Hydrochloric acid solution and sodium hydroxide solution yield water and dissolved sodium chloride
Step 1 – Write and balance the molecular form: HCl (aq) + NaOH (aq)  H2O (l) + NaCl (aq)
Step 2 – Determine which molecules dissociate and rewrite in ionic form: H+(aq) + Cl-(aq) + Na+(aq) + OH-(aq)  H2O(l) + Cl-(aq) + Na+(aq)
Spectator ions
Step 3 – Cancel ions that appear on both sides and rewrite what is left:
H+ (aq) + OH- (aq)  H2O (l)

8. Net Ionic Example #1
Nickel nitrate + sodium hydroxide  nickel hydroxide + sodium nitrate

9. Net Ionic Example #2 on the WS
Nickel nitrate + sodium hydroxide  nickel hydroxide + sodium nitrate

10. Net Ionic Decision Making Tree