OPIC: GRAVIMETRY SHOW THE SOLUTION The mercury in a 0.7152-g sample was precipitated with an excess of paraperiodic acid, H5IO6, according to the following reactions: 5 Hg+2 + 2 H5IO6 ---> Hg5(IO6)2(s) + 10 H+ The precipitate was filtered, washed free of precipitating agent, dried and found to weigh 0.3408-g. Calculate the percentage of Hg2Cl2 in the sample. Molar Masses: Hg5(IO6)2 = 1448.75 Hg2Cl2 = 472.09 Answer: 38.82% Hg2Cl2 An iron ore was analyzed by dissolving a 1.1324-g sample in concentrated HCl. The resulting solution was diluted with water, and the iron (III) was precipitated as the hydrous oxide Fe2O3·xH20 by the addition of NH3. After filtration and washing, the residue was ignited at a high temperature to give 0.5394 g of pure Fe2O3. Calculate (a) % Fe, and (b) % Fe3O4 in the sample Molar Masses: Fe2O3 = 159.69 Fe = 55.847 Fe3O4 = 231.54 Answer: 33.32% Fe and 46.04% Fe3O4
TOPIC: GRAVIMETRY
SHOW THE SOLUTION
The mercury in a 0.7152-g sample was precipitated with an excess of paraperiodic acid, H5IO6, according to the following reactions:
5 Hg+2 + 2 H5IO6 ---> Hg5(IO6)2(s) + 10 H+
The precipitate was filtered, washed free of precipitating agent, dried and found to weigh 0.3408-g. Calculate the percentage of Hg2Cl2 in the sample.
Molar Masses: Hg5(IO6)2 = 1448.75 Hg2Cl2 = 472.09
Answer: 38.82% Hg2Cl2
An iron ore was analyzed by dissolving a 1.1324-g sample in concentrated HCl. The resulting solution was diluted with water, and the iron (III) was precipitated as the hydrous oxide Fe2O3·xH20 by the addition of NH3. After filtration and washing, the residue was ignited at a high temperature to give 0.5394 g of pure Fe2O3.
Calculate (a) % Fe, and (b) % Fe3O4 in the sample
Molar Masses: Fe2O3 = 159.69 Fe = 55.847 Fe3O4 = 231.54
Answer: 33.32% Fe and 46.04% Fe3O4
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