The table shows the formulae of some ions.
| Name of ion | Formula of ion |
|---|---|
| sodium | Na⁺ |
| magnesium | Mg²⁺ |
| aluminium | Al³⁺ |
| chloride | Cl⁻ |
| oxide | O²⁻ |
| sulfate | SO₄²⁻ |
Use the table to write the formula of each compound.
magnesium chloride
aluminium oxide
sodium sulfate
The formula of magnesium oxide is MgO.
Explain why the formula is MgO and not MgO₂.
Zinc reacts with dilute hydrochloric acid. Hydrogen gas and zinc chloride solution are made.
The table shows three of the substances in this reaction, and pure water.
| Substance | State symbol |
|---|---|
| zinc powder | ? |
| hydrogen gas | ? |
| zinc chloride solution | ? |
| pure water | ? |
Complete the table. Use the state symbols (s), (l), (g) and (aq).
What does the state symbol (aq) mean?
55 exam-style questions on OCR GCSE Chemistry 3.1 Introducing chemical reactions, covering 3.1.1 Writing formulae and balanced chemical equations, 3.1.2 Formulae of compounds from ions, and state symbols, 3.1.3 Conservation of mass and observed changes in mass, 3.1.4 Half equations and balanced ionic equations, 3.1.5 The mole and the Avogadro constant, and 3.1.6 Stoichiometry, limiting reactants and reacting masses. Each one has a worked solution and a mark scheme showing where the marks go.