How do you write a balanced net ionic equation for the reaction of sulfurous acid with calcium hydroxide?
First write the balanced ionic equation, then retain only those elements that change form.
This may be a “thought exercise” because sulfurous acid may not exist in solution, so we are looking at a gas-solid reaction interface.
However, if we simply stick to the “acidity” (hydrogen ions) reacting with the “base” (hydroxide ions) we can make a conjecture of a reaction. Acids and bases react to form salts and water, so the water formation reaction is really the “net” reaction.
H2SO3 + Ca(OH)2 → CaSO3 + 2H2O
in ionic form:
The net ionic is then: