Required Practical 8: Water

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

  How to analyze and purify water
• What is potable water?

  Water that is safe to drink
• How does potable water differ from pure water?

  Potable water may contain dissolved solids
• What is the pH of pure water?

  7
• What indicates that a water sample is not pure?

  pH not equal to 7
• How do you check the pH of water?

  Using universal indicator paper
• What does an increase in mass of the evaporating basin indicate?

  Presence of dissolved solids in water
• What happens to dissolved solids when water evaporates?

  They form crystals on the basin
• What is the first step in testing water purity?

  Check the pH of the water
• What is the purpose of distillation in water purification?

  To remove dissolved solids from water
• What equipment is used in the distillation process?

  Conical flask and delivery tube
• What happens to water when it is heated in distillation?

  It evaporates and forms water vapor
• What occurs when water vapor enters a cold test tube during distillation?

  It condenses back into liquid water
• What is distilled water?

  Water with no dissolved solids
• What is the pH of distilled water?

  7
• What are the steps to analyze a sample of water for purity?

  1. Check the pH using universal indicator paper.
  2. Weigh an empty evaporating basin.
  3. Fill the basin with the water sample.
  4. Heat the water until it evaporates.
  5. Weigh the basin again to check for dissolved solids.
• How do you purify water by distillation?

  1. Place water sample in a conical flask.
  2. Heat the flask gently with a Bunsen burner.
  3. Collect water vapor in a delivery tube.
  4. Condense vapor in a cold test tube.
  5. Collect distilled water, which is pure.
• What are the differences between potable water and pure water?

  • Potable water: safe to drink, may contain dissolved solids, pH may vary.
  • Pure water: contains no dissolved solids, pH is 7.