Identification Of Common Gasses

Question 1

How do we test for chlorine ?

Answer 1

1. Test tube full of sample gas
2. Damp piece of blue litanies paper
3. Put it in the test tube
   If present: the paper will turn from blue to white meaning Chlorine is white
   May briefly turn red as the chlorine dissolved on the damp paper forming HCL

Question 2

What are the safety precautions for testing for chlorine ?

Answer 2

It is poisonous so wear a mask or do it in a fume cupboard

Question 3

How do we test for oxygen ?

Answer 3

1. Glowing splint (without flame but still glowing)
2. Get sample of gas in test tube and place splint in it
3. If oxygen is present the splint will relight as it’s giving it an abundance of oxygen

Question 4

How do we test for hydrogen ?

Answer 4

1. Get a test tube of your sample gas
2. Get a burning splint that’s still lit
3. Put the splint in the tube and if hydrogen is present there will be a loud squeaky pop !
   Heat energy provided but the flame causes the hydrogen to burn with the oxygen in the air

Question 5

How do we test for carbon dioxide ?

Answer 5

1. Gas sample in one tube and an aqueous solution of limewater in another tube connected via a plastic tube
2. Bubble the gas sample through the lime water and if the gas is carbon dioxide it causes the limewater to go cloudy
   Reason: calcium carbonate is a solid and all the little particles make it appear cloudy

Question 6

What are the four tests ?

Answer 6

Chlorine- blue litens paper turns white
Oxygen- relight a glowing splint
Hydrogen- squeaky pop
Carbon dioxide- turn limewater cloudy