Download Net Ionic Equations

Net Ionic Equations
A net ionic equation is an equation that shows only what changes in a reaction. You can think of it as Cliff notes for a
chemical reaction. To do a net ionic equation, you have to recognize what will ionize (break up) when placed in water.

Salts- these are ionic compounds. Any salt, as long as it is soluble in water (see solubility rules below), will break
up into its ions. Remember though that polyatomics stay together. If it is not soluble in water it is a solid and
doesn’t break up.

Molecular compounds – these are covalent compounds. They never ionize in solution – the most common one
you will run across is water.

Acids – these are always soluble in water, but they don’t all break up in water. To determine which acid breaks
up in water you must determine if it is a strong or a weak acid. Strong acids break up in water, which is why they
are so dangerous. To determine whether an acid is strong or weak, use the following guidelines:
Acids without oxygen in the formula (binary acids) – there are only three that are strong: HCl, HBr, and
HI. Any other binary acid will be weak – for example H2S or HF.
Acids with oxygen in the formula (ternary acids) – if the #O - #H is equal to or greater than 2, then the
acid is strong. H2SO4 is a strong acid, while H2SO3 is weak.
Acids with carbon in the formula (organic acids) – these are always weak acids.
Solubility rules for ionic compounds:
1. All common salts of the Group 1 (IA) elements and ammonium ion are soluble.
2. All common acetates and nitrates are soluble.
3. All binary compounds of Group 17 (VIIA) elements (other than F) with metals are soluble except those of silver,
mercury (I), and lead.
4. All sulfates are soluble except those of barium, strontium, lead, calcium, silver, and mercury (I).
5. Except for those in Rule 1, carbonates, hydroxides, oxides, sulfide, and phosphates are insoluble.
Example of a net ionic equation: barium nitrate + sodium sulfate  barium sulfate + sodium nitrate
Step 1 – write the molecular formula (include the states: s, l, g, or aq)
Ba(NO3)2(aq) + Na2SO4(aq)  BaSO4(s) + 2NaNO3(aq)
Step 2 – write the complete ionic equation by breaking up everything that will ionize in water
Ba+2(aq) + 2NO3-1(aq) + 2Na+1(aq) + SO4-2(aq)  BaSO4(s) + 2Na+1(aq) + 2NO3-1(aq)
Step 3 – write the net ionic equation by canceling out species that are identical on both sides of the equation.
Ba+2(aq) + 2NO3-1(aq) + 2Na+1(aq) + SO4-2(aq)  BaSO4(s) + 2Na+1(aq) + 2NO3-1(aq)
Ba+2(aq) + SO4-2(aq)  BaSO4(s)
In Class Examples
Magnesium sulfate + lead (II) nitrate
Hydrochloric acid + sodium hydroxide
Sodium chloride + nitric acid
Sodium nitrate + lead (II) iodide
Potassium + calcium fluoride