http://www .csun.edu /~hcchm 001/F reshChe mHa ndouts.htm l
1. Write the overall equation including the correct designations for the physical state of the substances
(s, l, g, aq). Balance this equation. Most of these kinds of equations are double displacement
reactions: AX + BY 6 AY + BX
2. For the total ionic equations, write strong electrolytes in solution in the form of aqueous ions.
(a) Strong acids. The common strong acids and their aqueous ions are:
HI Hydroiodic acid H (aq) + I (aq)
+-
HBr Hydrobromic acid H (aq) + Br (aq)
+-
HCl Hydrochloric acid H (aq) + Cl (aq)
+-
33
HNO Nitric acid H (aq) + NO (aq)
+-
44
HClO Perchloric acid H (aq) + ClO (aq)
+-
24 4
H SO Sulfuric acid 2 H (aq) + SO (aq)
+-2
(b) Strong bases. Strong bases are the hydroxides of the alkali (Group IA) and
alkaline earth (Group IIA) metals ions which are sufficiently soluble. The
common strong bases and their aqueous ions are:
LiOH Lithium hydroxide Li (aq) + OH (aq)
+-
NaOH Sodium hydroxide Na (aq) + OH (aq)
+-
KOH Potassium hydroxide K (aq) + OH (aq)
+-
2
Sr(OH) Strontium hydroxide Sr (aq) + 2 OH (aq)
+2 -
2
Ba(OH) Barium hydroxide Ba (aq) + 2 OH (aq)
+2 -
(c) Soluble salts. Determinations of the solubility of a salt may be made by
reference to SOLUBILITIES OF IONIC COMPOUNDS. Soluble salts are
written as their aqueous ions:
NaCl(aq) Sodium chloride Na (aq) + Cl (aq)
+-
24 4
K SO (aq) Potassium sulfate 2 K (aq) + SO (aq)
+-2
23 3
Li CO (aq) Lithium carbonate 2 Li (aq) + CO (aq)
+-2
34 4
Na PO (aq) Sodium phosphate 3 Na (aq) + PO (aq)
+-3
42 4 4 4
(NH ) SO (aq) Ammonium sulfate 2 NH (aq) + SO (aq)
+-2
3. For the total ionic equations, write the weak electrolytes in solution as their (predominantly)
molecular form. Weak electrolytes, or un-ionized substances, include (with examples):
(a) weak acids (b) weak bases (c) water
232 3 2
HC H O (aq) NH (aq) H O(l)
432
HCN(aq) (NH OH written as NH (aq) + H O(l)
4. For the total ionic equations, write insoluble substances as the total compound (in their
molecular form). Unstable substances are written in their decomposed forms. These substances
include (with examples):
(a) precipitates or insoluble reactants (b) gases (c) derived from unstable substances
32432
CaCO (s) CO (g) If NH OH, write NH (aq) + H O(l)
222322
Zn(OH) (s) SO (g) If H CO , write CO (g) + H O(l)
232322
Mg(OH) (s) SO (g) If H SO , write SO (g) + H O(l)
222
Ca(OH) (s) O (g), N (g)
5. For the net ionic equations, cancel any substances or ions that appear on both sides of the equation.
WRITING TOTAL AND NET IONIC EQUATIONS
