Qualitative analysis encompasses all the chemical tests we can use to find out which anions and cations are present in a compound. These tests are carried out in test tubes and the quality of the observations we make is key …
- changes in colour of a solution (including from / to colourless)
- bubbles / effervescence (remember we can’t see what the gas is, just that we have a coloured or colourless gas)
- formation of a precipitate and its colour, as well as the colour of the remaining solution e.g. formation of a deep blue precipitate in a colourless solution
- identifying gases using secondary tests such as damp blue or red litmus paper, or bubbling a gas through limewater
Identifying anions and cations
✓ carbonate, sulfate and halide ions
✓ ammonium ions
✓ flame test for metal cations
Identifying transition metal ions using ligand exchange reactions
✓ with ammonia
✓ with chloride ions
Using precipitation reactions to identify transition metal ions
✓ with hydroxide ions
✓ with carbonate ions