Question

How much chalcopyrite had to be mined to produce 100 pennies if reaction 1 had a percent yield of 64.00 % and all other reaction steps had yield of 100%?

Answer 1

Answer:

$m_{CuFeS_2}=554.44gCuFeS_2$

Explanation:

Hello,

During this process, the following chemical reactions are carried out:

$(1) 2 CuFeS_2 + 3 O_2 ---- > 2 CuS + 2 FeO + 2 SO_2\\(2) 2 FeO + SiO_2 ---- > 2 FeSiO_3\\ (3) 2 CuS ---- > Cu_2S + S\\(4) Cu_2S + S + O2 ----> 2 Cu + 2 SO_2$

Now, a typical penny, has about 3.0 g of copper, it means that 100 pennies have 300 g of copper, thus, we develop the following stoichiometric procedure to determine the sulfur that is consumed in the 4th reaction, because in the third one it is produced:

$n_{S}=300gCu*\frac{1mol Cu}{63.5gCu} *\frac{1mol S}{2molCu} =2.36molS$

Since the percent yield for the second, third and fourth chemical reactions is 100%, we now proceed to the third reaction to compute consumed cupric sulfide since it is produced in the first chemical reaction, thus:

$n_{CuS}=2.36molS*\frac{2molCuS}{1molS}= 4.72molCuS$

Finally, by using the first chemical reaction and the percent yield (represented by the by-moles relationship of cupric sulfide), one computes the required mass of chalcopyrite ($CuFeS_2$) with a molecular mass of 183.54g/mol considering the first chemical reaction:

$m_{CuFeS_2}=4.72molCuS*\frac{64mol CuS}{100molCuS} *\frac{2molCuFeS_2}{2molCuS} *\frac{183.54gCuFeS_2}{1molCuFeS_2} \\m_{CuFeS_2}=554.44gCuFeS_2$

Best regards