You have been given a 100 mL volumetric aliquot (exact volume) of a sample containing an unknown concentration of CrO42-. You perform gravimetric analysis of a 25 mL aliquot of the original 100 mL sample by precipitation with sufficient Ag+ (forming Ag2CrO4). The mass of the empty crucible is 26.252 g. The mass of the crucible containing the precipitate is 26.458 g.
(a) Determine the mass of precipitate formed.
(b) Report the concentration of the CrO42- in the original sample in molar concentration (M).
(c) Report the concentration of CrO42- in the original sample in parts per million (ppm).
(d) What is the molar concentration of Ag+ that must be used to just start the precipitation of Ag2CrO4 from a solution that is 1.0 x 10-6 M in CrO42- (Ksp = 1.1 x 10-12)?
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