Download - Copper Minerals
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Copper Mineralsa % composition exercise
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Simple Copper Sulfides
Chalcocite: copper (I) sulfide
Tenorite:
copper (II) sulfide
1. Write the formulas for each sulfide and determine the %Cu.
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Complex Copper Sulfides
Bornite Cu5FeS4
Chalcopyrite CuFeS2
2. From inspection (by looking), which ore has the highest %Cu? Calculate the %Cu in each to see if you’re right!
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Semiprecious Copper Gems
Malachite
CuCO3.Cu(OH)2
Azurite 2CuCO3.Cu(OH)2
3a. Determine the %Cu in each gem.
3b. Which contains more copper: 10.0 g of azurite or 9.00 g of malachite?
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Cuprite: copper (I) oxide
single crystal
more usual form (microcrystalline)
4a. Find the %Cu in cuprite.
4b. How many Cu atoms are there in a 5.25 g crystal of cuprite?
4c. If a sample contained 0.30 moles of Cu atoms, how many moles of oxygen atoms would it have?
While most copper compounds are blues or greens, there is one red one.
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Answer Key1. copper (I) sulfide = Cu2S; copper (II) sulfide = CuS
% Cu in Cu2S = {(2*63.5 g)/[(2*63.5 g)+32.1 g]}*100 = 79.8%
% Cu in CuS = [(63.5 g)/(63.5 +32.1 g)]*100 = 66.4%
2. With 5 Cu, bornite looks to have a higher %Cu than chalcopyrite with one Cu.
bornite = 63.3% Cu
chalcopyrite = 34.6% Cu
3a. azurite (3Cu, 8O, 2H, 2C)= 55.3% Cu
malachite (2Cu, 1C, 5O, 2H) = 57.5% Cu
3b. 10.0 g azurite * 0.553 = 5.53 g Cu
9.00 g malachite *0.575 = 5.18 g Cu, so AZURITE HAS MORE Cu
4a. copper (I) oxide = Cu2O; cuprite = 88.8% Cu
4b. 5.25 g sample* 0.888 = 4.66 g Cu
4.66 g Cu * (1 mole/63.5 g) * (6.02 x 1023 atoms/1 mole) = 4.42 x 1022 atoms
4c. Cu2O has one oxygen for every 2 copper atoms, so a sample with 0.30 mol. Cu would have (1/2)(0.30 mol) = 0.15 moles oxygen