Question

calculate the mass percentage composition of copper pyrites( CuFeS2).

Answer 1

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                 Let the number of moles of given copper pyrite (CuFeS2) = 1
Every 1 mole of copper pyrite contains 2 moles of Sulphur and 1 mole of each of Copper and Iron.
Gram molecular weight of 1 mole of copper pyrite =
=gram atomic weight of  Copper  + gram atomic weight of Iron + gram atomic weight of Sulphur
= 64+ 56+2(32)
= 184 grams
Calulations of mass percentage for 1mole each of element in 1 mole of copper pyrite:
Mass percentage of Copper in copper pyrite=
= (gram atomic weight of Copper*100)/ total gram molecular weight of copper pyrite
=(64*100)/184
= 34.78%
Mass percentage of Iron in copper pyrite=
= (gram atomic weight of Iron*100)/ total gram molecular weight of copper pyrite
=(56*100)/184
= 30.43%
Mass percentage of Sulphur in copper pyrite=
= (gram atomic weight of sulphur *100)/ total gram molecular weight of copper pyrite
=(64*100)/184
= 34.78%