Gravimetric analysis is a quantitative inorganic analysis method in which the amount of an analyte (ion or compound) is determined by measuring its mass. It is one of the most accurate and reliable techniques in analytical chemistry.
Principle:
- The analyte is converted into a pure, stable, and insoluble compound (precipitate).
- The precipitate is separated, purified, and weighed.
- From the mass of the precipitate, the amount of the original substance can be calculated using stoichiometry.
Steps in Gravimetric Analysis:
- Preparation: Dissolve the sample in a suitable solvent.
- Precipitation: Add a reagent to form an insoluble compound with the analyte.
- Filtration: Separate the precipitate from the solution.
- Washing: Wash the precipitate to remove impurities.
- Drying/Calcination: Dry or heat the precipitate to a constant weight.
- Weighing: Accurately weigh the purified precipitate.
- Calculation: Use the known chemical formula of the precipitate to calculate the amount of the analyte.
Example:
- Determining barium in a solution by precipitating it as barium sulfate (BaSO₄), then weighing the BaSO₄ to calculate the amount of barium.
Applications:
- Determining metal ions in solutions.
- Purity analysis of compounds.
- Standardizing solutions in laboratories.
Advantages:
- Highly accurate and precise.
- Simple equipment required.
Limitations:
- Time-consuming.
- Only works for substances that form pure and stable precipitates.