Test For cations

Question 1

Test for ammonium ion

Answer 1

Add aqueous sodium hydroxide to the solid or solution and heat (1)
Lower damp red litmus paper into gas produced (1)

If ammonium ions are present a pungent smelling gas is produced (1)
The gas produced turns DAMP red litmus paper blue (1)
The gas evolved in ammonia evolved from ammonium ions reacting with hydroxide ions form the sodium hydroxide

Question 2

Test for Cu2, Fe2 and Fe3

Answer 2

Add aqueous sodium hydroxide
Color of precipitate is reserved and recorded

For Cu2- Blue precipitate
For Fe2- Green precipitate
For Fe3- Brown precipitate

Question 3

Test for bromide, chloride and iodide

Answer 3

Add some dilute nitric acid to react and remove carbonate ions
Add a few drops of silver nitrate solution

Color of precipitate is reserved and recorded

Precipitate is a silver halide compound

chloride ion (Cl-)=white precipitate
Bromide ion (Br-)= cream precipitate
Iodide ion (I-)= Yellow precipitate

Question 4

Test for sulfate ions

Answer 4

Add DILUTE Hcl
Add a few drops of barium chloride
If sulfate ions are present a white precipitate will be formed (barium sulfate)

Question 5

Testing for carbonate ions

Answer 5

Add DILUTE Hcl
Bubble gas into limewater
If carbonate ions are present, CO2 is produced when reacting with Hcl
CO2 reacts with limewater to turn milky

Question 6

Test for water

Answer 6

Add liquid to ANHYDROUS copper sulfate
If liquid is water, white powder will turn blue as hydrated copper surface is formed and is a blue crystal
Doesn’t indicate if water is pure

Question 7

Test for pure water

Answer 7

Boiling point-100c
Freezing point-0c
Has to be precise