Metal Hydroxide Precipitates

• What should you be able to describe by the end of this video?

  Using sodium hydroxide to identify metal ions
• Why is it important to learn the tests for metal ions?

  They often appear in exams
• Which metal ions are tested using sodium hydroxide solution?

  Calcium, magnesium, and aluminium ions
• What happens when sodium hydroxide is added to calcium, magnesium, and aluminium ions?

  They produce a white precipitate
• How can you distinguish between calcium, magnesium, and aluminium ions after adding sodium hydroxide?

  Aluminium precipitate dissolves in excess sodium hydroxide
• What is the balanced chemical equation for calcium ions reacting with sodium hydroxide?

  Ca(NO₃)₂ + 2NaOH → 2NaNO₃ + Ca(OH)₂
• What does the state symbol for calcium hydroxide indicate?

  It indicates a solid precipitate
• What are the insoluble metal hydroxides formed when testing with sodium hydroxide?

  • Calcium hydroxide
  • Magnesium hydroxide
  • Aluminium hydroxide
• What color precipitate do copper(II) ions form with sodium hydroxide?

  Blue precipitate of copper(II) hydroxide
• What color precipitate do iron(II) ions form with sodium hydroxide?

  Green precipitate of iron(II) hydroxide
• What color precipitate do iron(III) ions form with sodium hydroxide?

  Brown precipitate of iron(III) hydroxide
• What is the significance of the equations shown for metal ions reacting with sodium hydroxide?

  They illustrate the chemical reactions involved
• Where can you find more questions on testing for metal ions?

  In the revision workbook
• What are the steps to identify metal ions using sodium hydroxide solution?

  1. Add sodium hydroxide to the solution.
  2. Observe the color of the precipitate.
  3. Use excess sodium hydroxide for aluminium ions.
  4. Write balanced chemical equations for reactions.