Tests for positive ions

Lithium flame colour

Red

Sodium flame colour

Yellow

Potassium flame colour

Lilac

Calcium flame colour 

Orange-red

Copper flame colour

Blue-green

Copper ii test

• Add sodium hydroxide solution

• Blue precipitate

Iron ii test

• add sodium hydroxide solution

• Green precipitate

Iron iii test

• add sodium hydroxide solution

• Orange-brown precipitate

test for ammonium gas

• Add sodium hydroxide solution and heat

• Use damp red litmus paper

• Paper turns from red to blue in the presence of ammonia

formula ammonium

NH₄ +

formula ammonia

NH₃

Test for hydrogen

Produces a squeaky pop with a lit splint

test for oxygen

relights a glowing splint

test for carbon dioxide

When bubbled through limewater it turns cloudy

Test for ammonia

turns damp red litmus paper blue

test for chlorine

turns damp blue litmus paper red and then bleached

Chemical test for water

• Add the solution to solid anhydrous copper sulphate

• White solid turns blue to show water is present

• Doesn’t show if the water is pure though

physical test for water

• boil the solution and record the boiling point

• if the boiling point is 100C than the solution is pure water

how to perform a flame test

• dip nichrome wire in HCl hold over a bunsen flame until no colour is seen

• dip into the compound you are testing

• hold the wire in a roaring flame and observe the flame colour