Purity, Formulations and Gas Tests

• What is the everyday definition of a pure substance?


  A substance with nothing added to it
• What characterizes a chemically pure substance?

  It melts at a specific temperature
• How can you test the purity of a substance?

  By comparing its melting or boiling point
• What effect do impurities have on the melting point of a substance?

  They lower the melting point and increase the range
• What effect do impurities have on the boiling point of a substance?

  They increase the boiling point and may increase the range
• What is a chromatogram?

  • A visual representation of substances
  • Used to analyze mixtures
  • Displays separation of components
• What are formulations?

  • Mixtures with a specific purpose
  • Consist of multiple components
  • Used in products like medicines and fuels
• What gas burns quickly with a pop sound?

  Hydrogen
• What happens to a glowing splint in the presence of oxygen?

  It relights
• What effect does chlorine have on damp litmus paper?

  It bleaches it white
• What happens to limewater when carbon dioxide is bubbled through it?

  It turns cloudy
• What is limewater?

  • An aqueous solution of calcium hydroxide
  • Used to test for carbon dioxide
  • Turns cloudy in its presence
• What are some examples of formulations?

  • Metal alloys
  • Cleaning products
  • Medicines
  • Food
  • Cosmetics
  • Fuels
  • Paints
• What is the R value in chromatography?

  It represents the ratio of distances
• What does a higher R value indicate in chromatography?

  A substance travels further on the chromatogram
• How do different substances affect the number of spots on a chromatogram?

  Different substances produce different spots