A sample of Fungicide Copper (ll) Sulfate pentahydrate, CuSO4·5H2O (249.68 g/mol), is contaminated with silica. In order to determine the percentage purity of the sample, 29.78 g of it is added to water. The solution formed is filtered to remove the insoluble silica. Aqueous barium chloride is then added to the filtrate until all of the sulfate ions are precipitated as barium sulfate (233.43 g/mol). The precipitate is collected, washed with distilled water, dried and weighed. The mass collected is 1.966 g. ## Give your answer to TWO decimal places ## Question 2 3 pts Skip to question text. Aluminum can be determined gravimetrically by reaction with a solution of 8-hydroxyquinoline (C9H7NO). The net ionic equation is: Al3++ 3C9H7NO → Al(C9H6NO)3 + 3H+ A mass of 17.84 g of Al(C9H6NO)3 (459.45 g/mol) was obtained by precipitating all of the Al3+ from a solution prepared by dissolving 7.92 g of a mineral. What is the mass percent of aluminum (26.98 g/mol) in the mineral sample? ## Give your answer to THREE decimal places ## Question 3 4 pts Skip to question text. A soluble fertiliser contains phosphorus in the form of phosphate ions (PO43-, 95.0 g/mol). To determine the PO43- content by gravimetric analysis, 3.18 g of the fertiliser powder was completely dissolved in water to make a volume of 388 mL. A 44.2 mL volume of this solution was pipetted into a conical flask and the PO43- ions in the solution were precipitated as MgNH4PO4. The precipitate was filtered, washed with water and then converted by heating into Mg2P2O7. The mass of Mg2P2O7 (222.6 g/mol) was 0.063 g. ## Report your answer to TWO decimal places ##
Posted on: Thu, 01 Aug 2013 21:30:56 +0000
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