Determination of Sulphate as Barium Sulphate Using Gravimetry with Drying of Residue

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DETERMINATION OF SULPHATE AS BARIUM SULPHATE USING GRAVIMETRY WITH DRYING OF RESIDUE NAME: AYISAH BRIGHT EXPERIMENT: A.2.2.2. AIM To determine the sulphate present in a sample by gravimetry. INTRODUCTION Gravimetry encompasses all techniques in which we measure mass or change in mass. There are four methods of gravimetry, namely, precipitation gravimetry, electrogravimetry, volatilization gravimetry and particulate gravimetry. In this experiment precipitation gravimetry, in which the signal is the mass of the precipitate, is used. Precipitation gravimetry is based on the formation of an insoluble compound following the addition of a precipitating reagent, or precipitant to a solution of the analyte. A precipitate for precipitation gravimetric analysis must be of low solubility, high purity and of known composition if its mass is to accurately reflect the mass of the analyte. Also, the precipitate must be in a form that is easy to separate from the reaction mixture. The steps involved in precipitation gravimetry are precipitation, digestion, filtration, washing, drying and weighing. The sulphate content of an unknown sample is to be determined in this experiment. It is precipitated in dilute HCl with barium chloride as barium sulphate (BaSO4). The formed BaSO4 precipitate is allowed to stand in solution with the analyte solution. It is then washed and separated from solution by filtration and dried. Then it is weighed and its mass recorded. CHEMICALS AND APPARATUS 1. 500ml beaker 2. 200ml beaker 3. Stirring rod 4. Heating plate 5. Suction pump 6. 0.05M Barium chloride solution 7. 1:1 HCl 8. Filter paper 9. Analytical

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