In chemistry, qualitative analysis is the determination of the chemical composition of a sample. It encompasses a set of analytical chemistry techniques that provide nonnumerical information about a specimen.
Qualitative analysis can tell you whether an atom, ion, functional group, or compound is present or absent in a sample, but it doesn't provide information about its quantity. Quantification of a sample, in contrast, is called quantitative analysis.
There are two branches of qualitative analysis namely:
The basic testing procedure for identifying a compound is as follows:
| Cation | Observations | Sample Salts |
|---|---|---|
| Ammonium (NH4+) | Colorless or white crystals/powder
pungent smell of ammonia |
Ammonium chloride (NH4Cl), Ammonium sulfate (NH4 )2SO4 |
| Potassium (K+), Sodium (Na+), Lead (Pb2+), Magnesium (Mg2+), Aluminum (Al3+), Zinc (Zn2+) | Colorless or white crystals/powder | Potassium, Calcium, Lead, Aluminum, Magnesium, Zinc salts |
| Iron (Fe2+) | light green powder | Ferrous sulfate (FeSO4 ), iron(II) chloride (Fecl2) |
| Iron (Fe3+) | brown powder | iron(III) chloride (Fecl3) |
| Colour from flame test | Likely ion |
| Brick red | Ca²+ |
| Crimson red | Li2+ |
| Lilac | K2+ |
| Golden yellow | Na+ |
| Deep greeen | Cu2+ |
| Blue | Pb2+ |
| Light green | Ba2+ |