Question

Chalcopyrite is an ore with the composition
CuFeS2. What is the percentage of copper in
a 24.6 grams sample of this ore?
Answer in units of %.

Answer 1

molar mass of CuFeS2 = atomic mass of Cu + atomic mass of Fe + 2 × atomic mass of S

atomic mass of Cu = 63.5 g/mol

atomic mass of Fe = 56 g/mol

atomic mass of S = 32 g/mol

now, molar mass of CuFeS2 = 63.5 + 56 + 2 × 32
= 63.5 + 56 + 64 = 183.5 g/mol

percentage of copper in 1 mole of CuFeS2 = atomic mass of Cu/molar mass of CuFeS2 × 100

= 63.5/183.5 × 100

= 34.6 %

hence, % of copper in a 24.6 gram sample of Chalcopyrite = 34.6 %