Lab #1: Gravimetric determination of precipitate
Gravimetry involves set of methods that are based on determining how much of a chemical compound of known composition is present and is related to the analyte by mass. Before beginning with the experiment, it is very essential to review the mass stoichiometry. In this lab, we make use of precipitation gravimetry, which is most commonly used gravimetric method, in which analyte is separated as a precipitate and is converted to a compound of known composition that can be weighed. The steps needed for precipitation gravimetry are: 1)
Weighing the substance to be analysed
Dissolving the substance making a solution.
Precipitation of the constituent from the solution made by adding a suitable reagent. 4)
Filtration to separate the precipitate from the solution
Washing the precipitate the eliminate the contaminants
Drying of the precipitate to a obtain a weighable mass
Calculating the percentage from the mass of the sample and precipitate.
The purpose of this experiment is to determine quantitatively the amount of sulphate in barium sulphate which is precipitated when barium chloride is added to a sulphate solution. The analyte used in this experiment is barium. To obtain this analyte in a weighable form, it is very essential that the precipitation of this analyte occurs completely to avoid the contamination. In this case, we have used barium chloride as our sample and we have to obtain a good amount of barium sulphate as a precipitate.
References: 1) http://www.phar.kufauniv.com/staff/aymen/1.pdf
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