c4.4

• What are the four carbon gases tested in the video?

  Chlorine, oxygen, hydrogen, and carbon dioxide
• What is the first step in testing for chlorine gas?

  You need a test tube full of the sample gas
• What happens to blue litmus paper when chlorine is present?

  It turns from blue to white
• Why might the blue litmus paper briefly turn red before turning white when testing for chlorine?

  Chlorine dissolves in water on the damp paper, forming hydrochloric acid
• What safety precaution should be taken when testing for chlorine?

  Wear a mask or do it in a fume cupboard
• What is used to test for oxygen gas?

  A glowing splint
• What happens to a glowing splint when it is placed in oxygen?

  It relights
• What is the test for hydrogen gas?

  A burning splint produces a squeaky pop when near hydrogen
• What causes the squeaky pop sound when testing for hydrogen?

  The heat from the flame causes hydrogen to burn with oxygen to form water
• What is the test for carbon dioxide gas?

  Bubbling the gas through lime water
• What happens to lime water when carbon dioxide is bubbled through it?

  It goes cloudy
• Why does lime water go cloudy when carbon dioxide is present?

  Calcium carbonate is formed, which is a solid
• What are the results of the tests for the four gases?

  • Chlorine: Turns damp blue litmus paper white
  • Oxygen: Relights a glowing splint
  • Hydrogen: Produces a squeaky pop with a lit splint
  • Carbon dioxide: Causes lime water to go cloudy
• What is the chemical reaction that occurs when carbon dioxide reacts with calcium hydroxide?

  Carbon dioxide reacts with calcium hydroxide to form calcium carbonate and water
• What is the appearance of calcium carbonate when formed in lime water?

  It appears cloudy
• How does the presence of chlorine affect the color of blue litmus paper?

  Chlorine bleaches the paper, turning it white
• If you wanted to test for the presence of oxygen in a gas sample, what would you use?

  A glowing splint