The active ingredient in a zinc nutritional supplement is ZnSO4-7H20 (molar mass

Question

The active ingredient in a zinc nutritional supplement is ZnSO4-7H20 (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 10.830 g. A 2.402 g sample of the finely ground tablets was dissolved in an acidic solution. The solution was neutized 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 0.264 g of Zn2P207 (molar mass 304.76 g/mol). What is the mass percent of ZnSO4 7H2O in each tablet? Number % ZnSO4·7H20 What is the average mass of the active ingredient ZnSO4 7H20 and inactive filler in each tablet? Number g ZnSO,.7H2O Number g inactive filler

Explanation / Answer

n = 10 tablets

total mass of 10 tablest = 10.83 g

1 tablet = 10.83/10 = 1.083 g

m = 2.402 g sample

mol of Zn2P2O7 = mass/MW = 0.264 / 304.76 = 0.00086625

mol of Zn = 2*0.00086625 = 0.0017325 mol of Zn

mol of ZnSO4*7H2O --> 0.0017325 mol of active

mass of active = mol*MW = 0.0017325*287.58 = 0.49823 g of activ eingredient

this is in 2.402 g

so

% of ZnSO4H2O = 0.49823 /2.402 * 100 = 20.75 %

Q2.

find average mass of activ eingredient in --> 1 tablet:

mass of table = 1.083 g

of which, 20.75% is active -_> 1.083*20.75/100 = 0.2247225 g is ZNSO4*7H2O

inactive mass --> (1.083 -0.2247225 ) = 0.8582775 g of inactive filler

per tablet

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