Because weak electrolytes do not completely dissociate into ions, whenever two ions can get together to form a weak electrolyte there will be a net ionic equation. For example,
HCl(aq) + NaC2H3O2(aq) → HC2H3O2(aq) + NaCl(aq)
Writing out the complete ionic equation we obtain:
H+(aq) + Cl-(aq) + Na+(aq) + C2H3O2-(aq) → HC2H3O2(aq) + Na+(aq) + Cl-(aq)
Removing the spectator ions we obtain the net ionic equation:
H+(aq) + C2H3O2-(aq) → HC2H3O2(aq)
Water is also considered to be a weak electrolyte. That is, only a small fraction of the H2O molecules in water dissociate to form H+ and OH- ions. Therefore, any reaction that leads to the formation of water will have a net ionic equation. Let's look at a classic example of an acid reacting with a base.
HCl(aq) + NaOH(aq) → NaCl(aq) + H2O(l)
Removing the spectator ions we obtain the net ionic equation:
H+(aq) + OH-(aq) → H2O(l)
Homework from Chemisty, The Central Science, 10th Ed.
4.19, 4.21, 4.23, 4.25, 4.27, 4.39, 4.41, 4.43, 4.45, 4.47, 4.49, 4.51, 4.53, 4.55, 4.57
