Oxidation-reduction reactions can be used for quantitative analyses of both solu
ID: 815354 • Letter: O
Question
Oxidation-reduction reactions can be used for quantitative analyses of both solutions and solid samples. These analyses are based on the stoichiometry of the balanced equation for the reaction. Standard solutions of known concentration are used to completely react with the unknown solution. The concentration of the standard solution and the volume used in the titration are accurately known and are used to calculate the concentration or amount of the analyte solution. The amount of iron in ore can be quantitatively determined by bleating a solution of the unknown with a standard solution of dichromate, Cr2O7^2- . The net ionic equation is Part A The titration of 25.0 mL of an iron(II) solution required 18.0 mL of a 0.285M solution of dichromate to reach the equivalence point. What is the molarity of the iron(II) solution? Part B The Fe2^+(aq) solution described in Part A was produced by dissolving 4.05 g of ore in acid. What was the percentage of Fe by mass in this ore sample?Explanation / Answer
Molarity of iron (II) in the sample = 1.2312M calculated according to balanced equation.
To get this molarity the amount of iron ore the sample should contain is 1.717g
But the sample is having 4.05g.
Thus the purity of sample or percentae of iron = (1.717x100)/4.05 = 42.39%
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