Hydroxide tests

• What is the purpose of using sodium hydroxide solution in this lesson?

  To identify certain metal ions
• What should students be able to do by the end of the video?

  Describe tests and write balanced equations
• Which students is this lesson intended for?

  Triple chemistry students
• What method was previously discussed for testing metal ions?

  Flame tests
• What metal ions can be tested using sodium hydroxide solution?

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

  They produce a white precipitate
• Why is it a problem that calcium, magnesium, and aluminium ions produce a white precipitate?

  They cannot be distinguished from each other
• What happens when excess sodium hydroxide is added to the aluminium precipitate?

  The aluminium precipitate dissolves
• How can you identify calcium ions after testing with sodium hydroxide?

  By performing a flame test
• What is the balanced 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 is a solid precipitate
• What are the three insoluble metal hydroxides formed with sodium hydroxide?

  • Calcium hydroxide
  • Copper(II) hydroxide
  • Iron(II) hydroxide
  • Iron(III) hydroxide
• What color precipitate do copper(II) ions form with sodium hydroxide?

  Blue precipitate
• What is the balanced equation for copper(II) ions reacting with sodium hydroxide?

  CuSO₄ + 2NaOH → Cu(OH)₂ + Na₂SO₄
• What color precipitate do iron(II) ions form with sodium hydroxide?

  Green precipitate
• What is the balanced equation for iron(II) ions reacting with sodium hydroxide?

  FeSO₄ + 2NaOH → Fe(OH)₂ + Na₂SO₄
• What color precipitate do iron(III) ions form with sodium hydroxide?

  Brown precipitate
• What is the balanced equation for iron(III) ions reacting with sodium hydroxide?

  FeCl₃ + 3NaOH → Fe(OH)₃ + 3NaCl
• What type of questions can be found in the revision workbook regarding sodium hydroxide tests?

  • Testing for metal ions
  • Writing balanced equations
  • Identifying precipitates