A 25.0-g sample of garden compost was analyzed for its chloride content. The sample was dissolved in water, and the chloride was precipitated as silver chloride; 1.58 g of dried precipitate was obtained. Calculate the mass percent of chloride in the sample.
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Molecular weight of Silver chloride (AgCl) = 143.32
1.58 grams of AgCl divided by molecular weight gives you moles of AgCl
1.58/143.32 = 0.011 moles
Since there's 1 atom of Cl in every AgCl molecule, you also have 0.011 moles of Cl in the sample.
The molecular mass of Cl is 35.5, so 0.011 moles x 35.5g/mol = 0.3905 g Cl
Now to calculate mass percent, which = grams of Cl/total mass of sample x 100%
0.3905g/25g = 0.01562
0.01562 x 100% = 1.56% Cl
1.58 grams of AgCl divided by molecular weight gives you moles of AgCl
1.58/143.32 = 0.011 moles
Since there's 1 atom of Cl in every AgCl molecule, you also have 0.011 moles of Cl in the sample.
The molecular mass of Cl is 35.5, so 0.011 moles x 35.5g/mol = 0.3905 g Cl
Now to calculate mass percent, which = grams of Cl/total mass of sample x 100%
0.3905g/25g = 0.01562
0.01562 x 100% = 1.56% Cl
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1.58g/25g=0.0632*100=6.32%AuCl2