Writing simplified ionic equations can also help students to understand the underlying reactions of an acid with a base, metal or carbonate. While students may have a good overview of the reaction and products from making salts, the simplified ionic equation can emphasise the ions actually involved in the chemical change.

For example, if nitric acid is treated with potassium hydroxide, what is the ionic equation?

The symbol equation is: HNO₃ + KOH _↓ KNO₃ + H₂O

Writing out the ions: H⁺_(aq) + NO^–_3(aq) + K⁺_(aq) + OH^–_(aq) ↓ K⁺_(aq) + NO^–_3(aq) + H₂O_(l)

Note that nitrate ions and potassium ions appear unchanged on both sides of the equation. These spectator ions are omitted to leave the simplified ionic equation: H⁺_(aq) + OH^–_(aq) ↓ H₂O_(l)

Now consider the ionic equation for the reaction of an acid with a metal carbonate and complete the activity.

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[A worked example, requiring re-ordering to encourage thinking about the small clear steps necessary, for students, in writing ionic equations]