Tests for Gases and water

• What are the two main substances tested for in the document?

  Gases and water
• Why is dipping a finger in liquid not the best test for water?

  It does not provide accurate results
• What is the first common gas tested for?

  Chlorine
• What happens when chlorine bleaches damp blue litmus paper?

  It turns white
• What may happen to the litmus paper when chlorine is present?

  It may turn red for a moment
• What is the second common gas tested for?

  Oxygen
• What is observed when oxygen is tested?

  A glowing splint reignites
• What is the third common gas tested for?

  Carbon dioxide
• What happens when carbon dioxide is bubbled through limewater?

  Limewater turns cloudy
• What is the fourth common gas tested for?

  Hydrogen
• What sound is produced when hydrogen is ignited?

  A 'pop' sound is heard
• What is the fifth common gas tested for?

  Ammonia
• What happens when ammonia is tested with damp red litmus paper?

  It turns blue
• What is a characteristic of ammonia?

  It has a very strong smell
• What is the first test for copper(II) sulfate?

  It is blue when dry
• What happens to copper(II) sulfate when it is bound to water?

  It forms lovely blue crystals
• What happens when blue hydrated copper(II) sulfate is heated?

  It drives off water and turns white
• What is the second test for copper(II) sulfate?

  It is white when anhydrous
• What is the final observation when copper(II) sulfate is tested?

  It leaves a white residue
• What are the tests for the five common gases?

  1. Chlorine: Bleaches damp blue litmus paper white
  2. Oxygen: Glowing splint reignites
  3. Carbon dioxide: Turns limewater cloudy
  4. Hydrogen: Produces a 'pop' sound
  5. Ammonia: Turns damp red litmus paper blue
• What are the properties of copper(II) sulfate in different states?

  • Hydrated: Blue crystals
  • Anhydrous: White powder
  • Heating: Turns white when water is driven off
• What is used as a test for water?

  Copper(II) sulfate
• What happens when copper(II) sulfate is bound to water?

  It forms lovely blue crystals
• What occurs when you heat blue hydrated copper(II) sulfate crystals?

  They drive off the water of crystallization
• What color does the anhydrous copper(II) sulfate powder have?

  White
• What happens if you add water to white copper(II) sulfate powder?

  It turns back to blue crystals
• What does the test for water involve with copper(II) sulfate?

  Adding it to see if it turns blue
• What does the presence of blue crystals indicate in the test for water?

  Water is present in the solution
• What does a pure sample of water mean in terms of substances?

  It consists of only one substance
• What physical properties are defined for pure water?

  Boiling point and freezing point
• At what temperature does pure water boil?

  $100 \, °C$
• At what temperature does pure water freeze?

  $0 \, °C$
• What should you conclude if the boiling point is not $100 \, °C$?


  The sample is not pure water
• What should you conclude if the freezing point is not $0 \, °C$?


  The sample is not pure water
• What are the steps to test for water using copper(II) sulfate?

  1. Use copper(II) sulfate as a test.
  2. Observe color change to blue for water presence.
  3. Heat blue crystals to remove water.
  4. Add water to white powder to see if it turns blue.
• What defines a pure substance in terms of physical properties?

  • Consists of only one substance
  • Has a specific boiling point
  • Has a specific freezing point