\"Native,\" or elemental copper can be found in nature, but most copper is mined
ID: 574521 • Letter: #
Question
"Native," or elemental copper can be found in nature, but most copper is mined as oxide or sulfide minerals. Chalcopyrite (CuFeS2) is one copper mineral that can be converted to elemental copper in a series of chemical steps. Reacting chalcopyrite with oxygen at high temperature produces a mixture of copper sulfide and iron oxide. The iron oxide is separated from CuS by reaction with sand (SiO2). CuS is converted to Cu2S in the process and the Cu2S is burned in air to produce Cu and SO2: 2CuFeS2+3O2 2CuS+2FeO+2SO2 2FeO+2SiO2 2FeSiO3 2CuS Cu2S+S Cu2S+S+2O2 2Cu+2SO2
Explanation / Answer
2CuFeS2+3O2 --------> 2CuS+2FeO+2SO2 (1)
2FeO+2SiO2------> 2FeSiO3 (2)
2CuS----> Cu2S+S (3)
Cu2S+S+2O2 ---------> 2Cu+2SO2 (4)
100 pennies = 155.5 gm , moles of Cu= mass/atomic weight= 155.5/63.5 =2.45
Atomic weight of Cu= 63.5 and molar mass of Cu2S= 2*63.5+32=159 g/mole
from Reaction-4, 2 moles of Cu is obtained from 1 mole of Cu2S if the reaction is 100% complete.
2.45 moles of Cu required 2.45/2=1.225 moles of Cu.
from reaction-3, 1 mole of Cu2S is produced fom 2 moles of CuS. Hence moles of CuS used= 1.225*2=2.45 moles
from reaction-1, 2CuFeS2+3O2 --------> 2CuS+2FeO+2SO2 (1)
2 moles of CuS is produced from 2 mole of CuFeS2. 2.45 moles of CuS requires 2.45 moles of CuFeS2. but the reaction is only 69%. moles of CuFeS2 used= 2.45/0.69 =3.55 moles
molar mass of CuFeS2= 63.5+56+64=183.5 g/mole, mass of CuFeS2 to be used= 3.55*183.5 gm =651 gm
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