Metal Ion Precipitates

• Sodium hydroxide solution


  Used to identify certain metal ions
• Using sodium hydroxide solution to identify metal ions

  1. Add sodium hydroxide solution

  2. Observe precipitate formed

  3. Determine metal ion based on precipitate
• Calcium ions, magnesium ions, and aluminium ions all produce a white precipitate when reacted with sodium hydroxide solution
• Distinguishing between calcium, magnesium, and aluminium ions

  1. Add excess sodium hydroxide solution

  2. Aluminium precipitate dissolves, allowing distinction from calcium and magnesium
• Flame test is needed to distinguish between calcium and magnesium ions
• Balanced chemical equation


  Shows the reactants and products of a chemical reaction
• Balanced chemical equation for reaction of calcium ions and sodium hydroxide

  Calcium nitrate solution + Sodium hydroxide solution → Sodium nitrate solution + Calcium hydroxide precipitate
• Balanced chemical equation for reaction of magnesium ions and sodium hydroxide


  Magnesium nitrate solution + Sodium hydroxide solution → Sodium nitrate solution + Magnesium hydroxide precipitate
• Balanced chemical equation for reaction of aluminium ions and sodium hydroxide

  Aluminium nitrate solution + Sodium hydroxide solution → Sodium nitrate solution + Aluminium hydroxide precipitate
• Copper(II) ions


  React with sodium hydroxide to form a blue precipitate of copper(II) hydroxide
• Balanced chemical equation for reaction of copper(II) ions and sodium hydroxide

  Copper(II) nitrate solution + Sodium hydroxide solution → Sodium nitrate solution + Copper(II) hydroxide precipitate
• Iron(II) ions


  React with sodium hydroxide to form a green precipitate of iron(II) hydroxide
• Balanced chemical equation for reaction of iron(II) ions and sodium hydroxide

  Iron(II) nitrate solution + Sodium hydroxide solution → Sodium nitrate solution + Iron(II) hydroxide precipitate
• Iron(III) ions


  React with sodium hydroxide to form a brown precipitate of iron(III) hydroxide
• Balanced chemical equation for reaction of iron(III) ions and sodium hydroxide

  Iron(III) nitrate solution + Sodium hydroxide solution → Sodium nitrate solution + Iron(III) hydroxide precipitate