A water-treatment process removes dissolved iron(III) ions by adding sodium hydroxide solution to iron(III) sulfate solution. An insoluble metal hydroxide forms.
| Substance or ion | Formula |
|---|---|
| iron(III) sulfate | Fe2(SO4)3\text{Fe}_2(\text{SO}_4)_3Fe2(SO4)3 |
| sodium hydroxide | NaOH\text{NaOH}NaOH |
| sodium sulfate | Na2SO4\text{Na}_2\text{SO}_4Na2SO4 |
| iron(III) ion | Fe3+\text{Fe}^{3+}Fe3+ |
| hydroxide ion | OH−\text{OH}^-OH− |
The other product of the reaction is sodium sulfate.
Explain how the charges of the ions determine the formula of iron(III) hydroxide.
Give the balanced symbol equation for the reaction.
State the colour of the precipitate formed.
93 exam-style questions on AQA GCSE Chemistry 8.3 Identification of ions by chemical and spectroscopic means, covering 8.3.1 Flame tests, 8.3.2 Metal hydroxides, 8.3.3 Carbonates, 8.3.4 Halides, 8.3.5 Sulfates, 8.3.6 Instrumental methods, and 8.3.7 Flame emission spectroscopy. Each one has a worked solution and a mark scheme showing where the marks go.