Question

The active ingredient in a zinc nutritional supplement is ZnSO4·7H2O (molar mass = 287.58 g/mol). Ten zinc tablets containing a mix of the active ingredient and an inactive filler were ground and mixed together thoroughly. The total mass of these ten tablets was 10.165 g. A 1.830 g sample of the finely ground tablets was dissolved in an acidic solution. The solution was neutralized with ammonia and subsequently warmed in a water bath. Addition of (NH4)3PO4 to the solution resulted in the precipitation of ZnNH4PO4. The precipitate was filtered and dried, then ignited to produce 0.234 g of Zn2P2O7 (molar mass = 304.76 g/mol). What is the mass percent of ZnSO4·7H2O in each tablet?

What is the average mass of the active ingredient ZnSO4·7H2O and inactive filler in each tablet?

Answer 1

Its all about Zinc ...So focus on Zinc only.......

Moles of Zn₂P₂O₇ = mass/molar mass = 0.234/304.76 =0.7678 millmoles

each mole of Zn₂P₂O₇ contains 2 Zinc atoms

so Total moles of Zn = 2 x 0.7678 = 1.5356 millmoles

Mass of one tablet = 10.165/10 =1.065gram

No of Tablets in 1.830 grams   = mass of sample used/Mass of one tablet

                                                   = (1.830)/1.0165 = 1.8 tablets

so

1.8 tablets contain , zinc millimoles = 1.5356 millmoles

1 tablet conation, zinc millimoles = (1.5356/1.8) millmoles = 0.8531 millmoles

So Each tablet contains 0.8531 ZnSO4·7H2O , Millmoles

Mass of ZnSO4·7H2O   per tablet = 0.8531x287.58 g/mol = 0.2453376 milligrams

Mass % of ZnSO4·7H2O = (Mass of ZnSO4·7H2O )/(total mass of one tablet )x100

                                            =(0.2453376/1.0165) x100 = 24.13%

                                 Very long question.....please post the 2nd part separately