1. Qualitative Analysis
Reactions that produce an INSOLUBLE SALT

2. Cations and Anions
When ionic compounds are dissolved into a solution they form cations and anions
Cations (like metals ions) have a positive charge
Anions (like non-metal groups) have negative charges

3. Remember! Metal ion Result of adding NaOH (aq) Cu2+ Fe2+ Fe3+
You will need to remember the colour of the precipitate formed for these metals?
REMEMBER: Common hydroxides are INSOLUBLE so they form precipitates
Metal ion
Result of adding NaOH (aq)
Cu2+
Fe2+
Fe3+
Pale blue precipitate of Cu(OH)2
Dirty green precipitate of Fe(OH)2
Rusty brown precipitate of Fe(OH)3

4. Tests for cations (+ve ions)
Li+, Na+, K+, Ca2+ using flame tests
NH4+ using NaOH(aq)
Cu2+, Fe2+ and Fe3+ using NaOH(aq)

5. Testing for NH4+ (“ammonium ion”)
Add NaOH (aq)
Warm gently
Test gas given off with damp red litmus paper
Ammonia gas is given off which turns the damp red litmus paper BLUE
Does anyone know why the
litmus paper changes colour?

6. Testing for Cl- ions
Add SMALL amounts of silver nitrate solution to salts containing halogen ions that have been dissolved in dilute nitric acid.
Type of ion (dissolved in HNO3(aq))
Result of adding dilute silver nitrate
Cl-
White precipitate of silver chloride

7. Testing for sulphate ions SO42-(aq)
Add SMALL amounts of barium chloride solution to salts containing sulphate ions that have been dissolved in dilute hydrochloric acid.
If sulphate ions are present, a white precipitate of barium sulphate is formed.

8. Testing for NO3- (nitrate ions)
Add NaOH (aq)
Add some SMALL pieces of aluminium foil
Warm gently
Test gas given off with damp red litmus paper
Ammonia gas is given off which turns the damp red litmus paper BLUE

9. Testing for carbonate ions CO32-(aq)
Add dilute hydrochloric acid
See if it is effervescent
(fizzes due to carbon dioxide gas being given off)

10. Testing for anions - Summary
Chloride (Cl-)
using dilute nitric acid and silver nitrate solution
Sulphate (SO42-)
using dilute hydrochloric acid and barium chloride solution
Carbonate (CO32-)
using dilute hydrochloric acid and identifying the carbon dioxide evolved
Nitrate (NO3-)
using NaOH and aluminum, then warming gently