8.4 - Qualitative Analysis
Qualitative analysis
- Qualitative analysis identifies which substances or ions are present in a sample.
- Quantitative analysis determines how much of a substance is present.
- A chemical test must give a result unique to that ion so it can be identified without ambiguity.
Precipitation reactions
- A precipitate is an insoluble solid that forms when two solutions are mixed.
- In a precipitation test, a reagent is added that forms an insoluble solid with the ion being tested.
- If that ion is present, a precipitate forms; its distinct colour or appearance identifies the ion.
- Both negative ions (anions) and positive ions (cations) can be identified using precipitation tests.
TermDefinition
Qualitative analysisAnalysis that identifies which substances or ions are present in a sample.
Quantitative analysisAnalysis that determines how much of a substance is present in a sample.
PrecipitateAn insoluble solid that forms in a solution during a chemical reaction, usually when two solutions are mixed.