Gravimetric Determination of Calcium Essay

1388 Words Aug 24th, 2014 6 Pages
Gravimetric Determination of Calcium

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
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One of the ways to obtain it is to carry the precipitation slowly and for this experiment, it is done by dissolving Ca2+ and C2O42- and raising the pH by thermal decomposition of urea.

The solution will be filtered to obtain the precipitate, and then it will be washed to remove impurities and dried to remove water as a possible source of error in the mass. Calcium oxide is the precipitate. CaC2O4 2H2O(s) → CaO(s) + CO(g) + CO2(g). By computing using correct gravimetric factors, one can get the mass of the calcium from the calcium oxalate dihydrate.

In performing the experiment, one will need 0.1 M HCl solution, ammonium oxalate, distilled water, four filter paper, methyl red indicator and urea as reagents. We got our reagents from our laboratory assistant of our school. As for the apparatus, one will need 25-mL volumetric pipette, two 250-mL beaker, analytical balance, desiccator, funnel support, glass funnel, glass rod, hot plate, oven, two petridish, one suction bulb and watch glasses. Before we had starting the experiment, we cleaned all the apparatuses to avoid possible source of error in the process.
The methods we use in conducting the experiment are as follows: first, we rinsed the 25-mL pipette by using a small amount of the unknown sample. We prepared two 250-mL beaker and labeled it as trial one and the other trial two. We transferred the duplicated 25mL of the

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