21.39 In one step of the industrial process for producing copper from chalcopyri
ID: 508673 • Letter: 2
Question
21.39 In one step of the industrial process for producing copper from chalcopyrite (CuFeS2), molten copper (I) sulfide is reduced with a blast of hot air: Cu2S(l) O2 (g) 2 Cu() SO2(g) (a) How many kilograms of Cu2S must be reduced to account for the world's annual copper production of about 1.4 x 1010 kg? (b) How many liters of SO2 at STP are produced as a byproduct? (c) If all the SO2 escaped into the atmosphere and were converted to sulfuric acid in acid rain, how many kilo- grams of H2SO4 would there be in the rain?Explanation / Answer
Ans. Molar mass of Cu-atom = 63.546 g/ mol
Molar mass of Cu2S = 159.158 g/ mol
1 mol Cu2S consists of 2 Cu-atoms and 1 S-atom. That is-
#A. there are 2 moles of Cu-atom in 1 mol of Cu2S.
#B. Given, Mass of Cu = 1.4E10 kg = 1.4 x 1010 kg ; [E = 10E]
= 1.4 x 1013 g ; [1 kg = 1000 g]
Moles of Cu-atoms = Mass/ Molar mass
= 1.4 x 1013 g / (63.546 g/ mol)
= 2.20 x 1011 mol
Now,
2 mol Cu-atom is equivalent to 1 mol Cu2S
Or, 1 mol Cu- - - - (1/2) mol Cu2S
Or, 2.20 x 1011 mol - - - (1/2) x (2.20 x 1011) mol Cu2S
= 1.10 x 1011 mol Cu2S
Ans, Mass of Cu2S = Moles x molar mass
= 1.10 x 1011 mol x (159.158 g/ mol)
= 1.75 x 1013 g
= 1.75 x 1010 kg
So, 1.4 x 1010 kg Cu-atom = 2.20 x 1011 mol Cu-atom is equivalent to 1.10 x 1011 mol Cu2S = 1.75 x 1013 g Cu2S.
Result:
There are 2 moles of Cu-atom in 1 mol of Cu2S. 1.4E10 kg of Cu is 2.20 x 1011 mol Copper. The molecular mass of Cu2S is 159.158 g/ mol. 1.75 x 1013 kg of Cu2S would be required.
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