1. Unit 3: Chemical Equations and Stoichiometry
Net Ionic Equations

2. Write out the chemical equation for the reaction below.
Hydrochloric acid solution and sodium hydroxide solution yield water and dissolved sodium chloride

3. 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 what compounds dissociate and which do not

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

5. Net Ionic Rules Soluble Compounds Insoluble Compounds
Which molecules dissociate???
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
Soluble Compounds
Insoluble Compounds
Compounds of Group 1 elements
Ammonium (NH4+) compounds
Chlorides (Cl‐), bromides (Br‐), and iodides
(I‐), except those of Ag+, Hg2+2, and Pb+2
Nitrates (NO3‐), nitrites (NO2‐1), acetates
(CH3CO2‐), chlorates (ClO3‐), and
perchlorates (ClO4‐)
Sulfates (SO4‐2), except those of Sr+2, Ba+2, Pb+2, and Hg2+2
Carbonates (CO3‐2), chromates (CrO4‐2),
oxalates (C2O4‐2), and phosphates (PO4‐3),
except those of the Group 1 elements and
NH4+
Sulfides (S‐2), except those of the Group 1
and 2 elements and NH4+
Hydroxides (OH‐) and oxides (O‐2), except those of the Group 1 and 2 elements, and NH4+

6. 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

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:
H+ (aq) + OH- (aq)  H2O (l)

8. Net Ionic Example – WS #1
Sodium metal + water  sodium hydroxide + hydrogen gas

9. Net Ionic Decision Making Tree