Testing For Gases D. Crowley, 2008

Testing For Gases To know how to test for different gases Wednesday, April 18, 2018 To know how to test for different gases

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

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

Reactions Magnesium + Hydrochloric Acid Calcium Carbonate + Hydrochloric Acid Manganese Dioxide + Hydrogen Peroxide

Magnesium + Hydrochloric Acid  Magnesium Chloride + _______________ 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 + _______________

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)

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

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

Combustion Reaction If the reaction needs oxygen from the air it is a combustion reaction

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

Explosives

Explosives

Explosives

Explosives

Explosives

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

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…