Identifying Gases
You need to know how to identify various unknown gases. Read through this page then test yourself to check if you can remember them all. Once you’ve got them memorised, it’s easy marks to pick up on the exam.
Test for hydrogen gas
You can test for hydrogen gas by placing a lit splint near to the open end of a test tube containing the gas. If the gas is hydrogen, it will burn with a squeaky pop.
Test for oxygen
The test for oxygen is to insert a glowing splint into a test tube containing an unknown gas. If the splint relights, the gas is oxygen.
Test for carbon dioxide
You can test to see if a gas is carbon dioxide by bubbling it through limewater (aqueous calcium hydroxide). If the limewater turns cloudy, carbon dioxide is present. The mixture turns cloudy due to the formation of calcium carbonate which is an insoluble white precipitate.
Test for chlorine gas
You can test for chlorine gas by placing a piece of damp litmus paper above the test tube containing your unknown gas. If the litmus paper is bleached (turns white), the gas is chlorine.
Did you know…
Every time you breathe, you exhale around 25 sextillion molecules of oxygen – so many that within a just a single day’s breathing you will in all likelihood inhale at least one molecule from every person who has ever lived.
Next Page: Identifying Ions