Chemical tests

Test for hydrogen

Test for hydrogen

Lit splint squeaky pop

Test for Oxygen

Glowing splint relights

Test for Carbon Dioxide

Boil through limewater, limewater goes cloudy

Test for ammonia

Damp RED litmus paper turns blue

Test for chlorine

Damp BLUE litmus paper turns red then white

Test for presence of water using anhydrous copper sulphate

Add water, white —> blue

Describe a physical test to show whether a sample of water is pure or not

Boil at 100 degrees C

Describe how to carry out a flame test

Dip platinum or nichrome wire into concentrated HCl to remove impurities

Dip into salt

Hold in blue flame (non luminous)

Observe colour

What are the properties of a platinum or nichrome wire

Inert (unreactive)

High melting point

What is the colour formed in the flame test for Li+

Red

What is the colour formed in the flame test for Na+

Yellow

What is the colour formed in the flame test for K+

Lilac

What is the colour formed in the flame test for Ca2+

Orange-Red

What is the colour formed in the flame test for Cu2+

Blue-green

Describe the test for NH4+

Add NaOH

Heat gently: NH4+ + OH- —> NH3 + H2O

Test gas with damp red litmus paper to turn blue

Describe the test for Cu2+ using sodium hydroxide solution

dissolve in distilled water

Add a few drops of sodium hydroxide NaOH

Observe colour of precipitate

Blue

Describe the test for Fe2+ using sodium hydroxide solution

dissolve in distilled water

Add a few drops of sodium hydroxide NaOH

Observe colour of precipitate

Green

Describe the test for Fe3+ using sodium hydroxide solution

dissolve in distilled water

Add a few drops of sodium hydroxide NaOH

Observe colour of precipitate

orange-brown

Describe the test for Cl- using acidified silver nitrate solution

Acid to rid of impurities

White precipitate

Describe the test for I- using acidified silver nitrate solution

Acid to rid of impurities

Yellow precipitate

Describe the test for SO42- using acidified barium chloride solution

Add HCl to remove impurities

Add BaCl2 (aq)

White precipitate (BaSO4)

Describe the test for CO32- using HCl and identifying the gas involved

Add HCl

Fizzing

CO2 - bubble through limewater, limewater goes cloudy.