8.2 identification of common gases

test for hydrogen

hold a burning splint at the open end of a test tube of the gas

positive result for hydrogen test

splint burns rapidly and produces a squeaky pop

test for oxygen

insert a glowing splint into a test tube of the gas

positive result for oxygen test

splint relights (it bursts into flames)

test for carbon dioxide

draw some gas through a gas syringe and bubble through limewater

positive result for carbon dioxide test

limewater turns cloudy/milky

what is limewater

an aqueous solution of calcium hydroxide Ca(OH)₂

this means it is calcium hydroxide dissolved in water

test for chlorine

insert damp (blue) litmus paper into the mouth of the test tube

positive result for chlorine test

bleaches blue litmus paper and turns it white