common gases

• Common Gases


  • Carbon dioxide
  • Oxygen
  • Hydrogen
• Carbon Dioxide (CO2)


  • Colourless, odourless, tasteless gas
  • More dense than air
  • Doesn't support combustion
  • Air has 1% of it
• Limewater + Carbon dioxide

  Calcium carbonate (Chalk) + Water
• Ocean acidification


  • Forms carbonic acid when dissolved in water
  • Affects the ability of corals to grow their skeletons and form coral reefs
  • Corals become more vulnerable to disease and destruction
• Uses of Carbon Dioxide

  • Plants use it to make glucose during photosynthesis
  • Used in fire extinguishers – more dense than air - flame cant burn in it
  • Makes up the bubbles in fizzy drinks
• Producing Carbon Dioxide


  Hydrochloric acid + Calcium carbonate -> Calcium Chloride + Water + CO2
• Carbon dioxide doesn't support combustion
• Properties of Oxygen


  • Need it for cellular respiration to release energy from food
  • Colourless, odourless, tasteless gas
  • 20% of air is oxygen
  • Soluble in water – fish respiration
  • Produced by plants during photosynthesis
• Oxygen and the fire triangle

  • Oxygen supports combustion
  • and is needed for combustion
• Oxygen reacts with iron

  To produce rust (iron oxide)
• Properties of Hydrogen


  • Colourless odourless gas
  • Smallest element
  • Less dense than air
  • Explosive when in contact with air
  • Hydrogen reacts with oxygen in the air to produce water vapour
• Chemical nomenclature


  • H₂
  • H₂O
  • Number of atoms of each element in the molecule
  • 3H₂O
  • Number of molecules