Chemical tests

Hydrogen

Lit splint squeaky pop

Oxygen

Glowing splint relights

Carbon dioxide

Turns limewater cloudy

Ammonia

Turns damp red litmus paper blue

Chlorine

Turns damp blue litmus paper red then white

Lithium (flame)

red

Sodium (flame)

yellow

Potassium (flame)

lilac

Calcium (flame)

Brick red

Copper (flame)

blue-green

NH4+

Add sodium hydroxide, heat gently, ammonia gas is given off

Cu2+

Add sodium hydroxide, blue precipitate

Fe2+

Add sodium hydroxide, green precipitate

Fe3+

Add sodium hydroxide, brown precipitate

Cl-

Dilute nitric acid, sliver nitrate, white precipitate

Br-

Dilute nitric acid, silver nitrate, cream precipitate

I-

Dilute nitric acid, silver nitrate, yellow precipitate

SO42- test

Dilute HCl, barium chloride, white precipitate

CO32- test

Dilute HCl, CO2 produced (effervescence)

Water

Anhydrous copper sulphate turns from white to blue

Pure water

Boils at 100°C

Freezes at 0°C

Alkenes

Bromine water goes orange to colourless

Methyl orange indicator

Goes from red to orange in presence of alkaline

Phenolphthalein indicator

Goes from colourless to pink in presence of alkaline