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Gravimetric Determination of Calcium

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Gravimetric Determination of Calcium ABSTRACT Determining the mass of a pure compound is a method of a gravimetric analysis. One of the gravimetric analyses is the precipitation; it is a method of separating the analyte from the unknown sample as a precipitate where it will be filtered and converted into a known composition that can be weighed to determine its mass (Skoog et al, 2013). Determining the mass of calcium by using gravimetric analysis was the objective of the experiment. A 25 mL of unknown sample was used to analyze its calcium component. This sample was diluted with 25mL of distilled water in a beaker. It was converted into a soluble precipitate by adding 25 mL of ammonium oxalate solution and 15 g of solid urea. Since …show more content…

We made sure to rinse the glass rod before removing it to the beaker. Then we added up 15 g of solid urea to each sample. We boiled the solution for 30 minutes up until the indicator turns yellow. After boiling, we filtered it each through a funnel. The remaining solid from the beaker will be transfer to the funnel by adding 3mL of ice cold water to the beaker. We made sure that all of the precipitate has been transferred. After that, we used 10 mL of ice cold water to rinse each beaker and pour the washings over the precipitate. We transferred the precipitate in to the petridish, but before that we weighted first the petridish with the filter paper so that we can get the grams of the CaC2O4 2H2O precipitate later. We dried the precipitate in an oven set at 105oC for 1 hour. After that, we placed it inside the desiccator for 30 minutes to cool down the heat. Then instantly we weigh the petridish with CaC2O4 2H2O precipitate. In order to get the weight CaC2O4 2H2O precipitate, we subtracted the mass of the petridish alone from the mass of the petridish with CaC2O4 2H2O precipitate. And for determining the weight of Ca in the CaC2O4 2H2O precipitate, we use stoichiometry. We also computed for the average weight of calcium. III. RESULTS AND DISCUSSION Sample No. Trial 1 Trial 2 Volume of sample analyzed, mL 25 mL 25 mL Weight of

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