Results and Calculations
Questions to be answered
This experiment allowed students to find out the amount of sulphate by gravimetric method, to carry out vacuum filtration of BaSO4 precipitate and to use a desiccator correctly.
The experiment started out with the preparation of porcelain Gooch crucible followed by the preparation of BaSO4 by reacting BaCl with Na2SO4 which was slightly acidified by concentrated HCl. Next was the washing and filtering of BaSO4 precipitate using vacuum filtration. Upon drying and cooling, the weight of the precipitate was obtained using analytical weighing balance.
The weight of the barium sulphate precipitate was 0.1897 grams and the concentration of sulphate is 3.12192 g/L.
The purposes of this experiment were for students to be able to determine the amount of sulphate by gravimetric method, to carry out vacuum filtration of BaSO4 precipitate and lastly, to use the desiccator correctly.
Gravimetric analysis is one of the methods used in analytical chemistry for the quantitative determination of an analyte based on the weight of a solid.
The quantitative determination of a substance involves isolation of an ion in solution by a precipitation reaction with an appropriate reagent. Then, the precipitate can be collected by filtering, washing the precipitate free of contaminants, conversion of the precipitate to a product of known composition, and finally weighing the precipitate and determining its mass by difference. From the mass and known chemical composition of the precipitate, the amount of the original ion can be determined.
Several requirements must be met for gravimetric analysis to be quantitative. These are:
The precipitate to be separated must be obtainable in pure compound with a known stoichiometry.
The reaction must go essentially to completion (i.e., the solubility product for the solid must be very...