Qualitative Analysis
In qualitative analysis you test for the substances present but do not attempt to find out the amounts. The first step is to obtain pure samples of the substances to be tested. This involves the separation of the components on mixtures by a physical method.
There are quite a few methods:
- Evaporation or distillation may be used to remove unwanted liquids from solids or to obtain a pure liquid from one that is contaminated by dissolved solids.
- Fractional distillation may be used to separate pure liquids from mixtures
- Chromatography may be used to obtain pure solids from solutions containing a number of dissolved solids.
There are a number of tests that are carried out on pure substances:
- Initial observations
- Flame tests
- Tests on solutions for presence of ions: Positively charged ions are identified by reacting solutions with alkaline solutions. Negatively charged ions are detected in solution by specific tests.
