Testing For Gases

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Testing For Gases

• D. Crowley, 2008

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Testing For Gases

• To know how to test for different gases

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Gases

• How could you find out which gas is in this jar?

• Are the following comments correct?
• It must be oxygen as it is see-through like the
  oxygen in the air
• We could sniff it to see if it smells
• We could breathe it in to see if it is oxygen
• We could test what it reacts with

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Tests

• You are going to be given 3 reactions each
  produces a gas
• Your task is to identify what gas is produced
  remember the tests for the gases -
• Oxygen relights a glowing splint
• Carbon dioxide turns limewater cloudy when
  bubbled through
• Hydrogen produces a squeaky pop when a lit
  splint is placed in the gas

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Reactions

• Magnesium Hydrochloric Acid
• Calcium Carbonate Hydrochloric Acid
• Manganese Dioxide Hydrogen Peroxide

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Reactions

• The reactions are below can you use your
  findings from the experiment to finish the
  equations?
• Magnesium Hydrochloric Acid ? Magnesium
  Chloride _______________
• Calcium Carbonate Hydrochloric Acid ? Calcium
  Chloride Water _______________
• Manganese Dioxide Hydrogen Peroxide ? Manganese
  Dioxide Water _______________

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Reactions

• Word Equations
• Magnesium Hydrochloric Acid ? Magnesium
  Chloride Hydrogen
• Calcium Carbonate Hydrochloric Acid ? Calcium
  Chloride Water Carbon Dioxide
• Manganese Dioxide Hydrogen Peroxide ? Manganese
  Dioxide Water Oxygen
• (Manganese Dioxide is a catalyst (not used up in
  the reaction)

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Explosives

• What are explosives?
• When a chemical releases a large amount of energy
  very quickly an explosion occurs

• An explosion is a chemical reaction which causes
  huge amounts of gas to form as well as releasing
  a lot of heat

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Oxygen

• The chemical reactions need oxygen to take place
• Sometimes this oxygen comes from the air
• Sometimes the substance contains enough oxygen
  for the reaction to occur without additional
  oxygen

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Combustion Reaction

• If the reaction needs oxygen from the air it is a
  combustion reaction

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Decomposition Reaction

• If the reaction does not need additional oxygen
  from the air it is a decomposition reaction

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Explosives
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Explosives
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Explosives
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Explosives
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Explosives
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Explosives

• Chemicals designed to explode are called
  explosives.
• Some everyday chemicals can explode, e.g. natural
  gas mixed with the right amount of oxygen and
  heated to a high temperature

• Exploding natural gas was a real danger for coal
  miners in the 18th century. Whilst cutting away
  at the coal large amounts of methane were often
  released which exploded due to the high
  temperatures of the flames in the lamps they used
  - the Davy lamp reduced this risk by using a wire
  mesh to conduct heat away from the flame

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Uses

• Explosives are used to blast rock from quarries,
  build roads through hills, move bullets from the
  chamber and for fireworks.
• There are lots of examples of explosives,
  including gunpowder, nitroglycerine and dynamite