The amount of iron in ore can be quantitatively determined by titrating a soluti
ID: 1054073 • Letter: T
Question
The amount of iron in ore can be quantitatively determined by titrating a solution of the unknown with a standard solution of dichromate, Cx_2Oy^2-. The net ionic equation is The titration of 25.0 mL of an iron(ll) solution required 18.0 mL of a 0.230 M solution of dichromate to reach the equivalence point. What is the molarity of the iron(ll) solution? Express your answer to three significant figures and include the appropriate units. The Fe^2+ (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
The concentration of iron (II) solution is found to be 0.994 M (i.e) 0.994 moles/l. 1000 mL of solution contains 0.994 moles of Iron (II).
Then 25 mL of solution contains, (25x0.994)/1000 moles of Iron.
The moles of Iron present per 25 mL of the solution is 0.02485 moles.
We know that Number of moles = Mass / Molecular Mass, where the molecular mass of Iron is 55.845
Substitute the known values to find the mass of iron present in the sample.
Mass = 0.02485x55.845 = 1.3877 g
Mass of ore taken = 4.05g
Therefore, % of Fe present in the sample = (1.3877/4.05) x 100 = 34.26
% by weight of Fe present in the sample = 34.26 %
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