Calc % Ag in Alloy: 0.6353g Ag2/ 0.5000g alloy x 100% = 12.9%

[orchidee7]

Homework Statement

An alloy of copper and silver weighing 0.5000 grams is dissolved in HNO₃ and treated with H₂S to precipitate both CuS and Ag₂S. It is found that the solid sulphides weigh 0.7300 grams. Calculate the percentage of Ag in the alloy. (12.9 %)

2Ag⁺(aq) + H₂S(aq)→ Ag₂S(s) + 2H⁺(aq)
Cu⁺²(aq) + H₂S(aq)→ CuS(s) + 2H⁺(aq)

Homework Equations

mass of Ag/mass of alloy = % of Ag

The Attempt at a Solution

I'm not too sure how to start this question…

So far, I have

0.7300 g Ag₂S x 1 mol / 215.74 g Ag₂
= 2.945 x 10^-3 mol Ag₂S

2.945 x 10^-3 mol Ag₂S x 215.74 g Ag₂/ 1 mol Ag₂S
= 0.6353 g Ag₂I'm not sure if I'm on the right track here?

 

[Bystander]

You have a system of two equations in two unknowns.