1. Testing For Gases
D. Crowley, 2008

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

3. 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

4. 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

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

6. 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 + _______________

7. 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)

8. 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

9. 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

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

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

12. Explosives

13. Explosives

14. Explosives

15. Explosives

16. Explosives

17. 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

18. 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…