Answer to Question #98575 in General Chemistry for Beverlie

Question

2CuFeS₂ + 3O₂ → 2CuS + 2FeO + 2SO₂

2FeO + 2SiO₂ → 2FeSiO₃

2CuS → Cu₂S + S

Cu₂S + S + 2O₂ → 2Cu + 2SO₂

1. An average copper penny minted in the 1960s contained about 3.000 g of copper. How much chalcopyrite had be mined to produce 100 pennies?
2.How much chalcopyrite had to be mined to produce 100 pennies if reaction 1 had a percent yield of 90.00 % and all other reaction steps had yield of 100%?
3. How much chalcopyrite had be mined to produce 100 pennies if each reaction involving copper proceeded in 90.00 % yield?

Answer 1

1)One Copper penny contains 3 g of Copper.

100 Copper Pennies contains 300 g of Copper

No of moles of $Copper=300/63.546=4.721$

No of moles of $chalcopyrite=4.721$

Mass of chalcopyrite to be mined is $4.721×183.53=866.443g(Answer)$

2)$2CuFeS₂ + 3O₂ → 2CuS + 2FeO + 2SO₂$

x moles 9x/10 moles

All other reactions have 100% yield.

So no of moles of copper produced is 9x/10 moles.

One Copper penny contains 3 g of Copper.

100 Copper Pennies contains 300 g of Copper.

No of moles of $Copper=300/63.546=4.721$

$9x/10=4.721$

$x=4.721×10/9$

$x=5.24moles$ of Chalcopyrite.

Mass of chalcopyrite to be mined is $5.24×183.53=962.72g(Answer)$

3)$2CuFeS₂ + 3O₂ → 2CuS + 2FeO + 2SO₂$

x moles 9x/10 moles

$2CuS → Cu₂S + S$

9x/10 81x/200

$Cu₂S + S + 2O₂ → 2Cu + 2SO$

81x/200 729x/1000

One Copper penny contains 3 g of Copper.

100 Copper Pennies contains 300 g of Copper

No of moles of $Copper=300/63.546=4.721$

$729x/1000=4.721$

$x=4.721×1000/729$

$x=6.48 moles$ of Chalcopyrite.

Mass of chalcopyrite to be mined is $6.48×183.53=1188.54g(Answer)$