Test for Gases

1) HYDROGEN GAS - colourless and odourless



Test for gas: hold a lighted splint over the mouth of the test tube.
Observation: Lighted splint extinguished with a 'pop' sound.

2) OXYGEN GAS - colourless and odourless




Test for gas: Place a glowing splint into the mouth of the test-tube.
Observation: Glowing splint is rekindled.

3) CARBON DIOXIDE GAS - colourless and odourless

refer to 'test for carbonate ion' video

Test for gas: Pass the gas into calcium hydroxide(limewater) solution.
Observation: White ppt formed in limewater.
(Limewater turned chalky/milky is NOT accepted.)

4) CHLORINE GAS - yellowish green and choking


Test for gas: Hold a damp blue litmus paper over the mouth of the test-tube.
Observation: Blue litmus paper turns red and then bleached.

5) AMMONIA GAS - colourless and pungent


Test for gas: Hold a damp red litmus paper over the mouth of the test-tube.
Observation: Red litmus paper turns blue.

6) SULFUR DIOXIDE GAS - colourless and choking


Test for gas: Bubble the gas evolved into the potassium dichromate (VI) solution
Observation: Potassium dichromate(VI) solution turns from orange to green.