Copper is extracted from ore through 3 sequential (unbalanced) reactions in aqueous solution. In reaction 1, the chalcopyrite (CuFeS₂(s)) in the ore reacts with excess ferric (Fe³⁺) ions to form dissolved Cu²⁺ and ferrous (Fe²⁺) ions, while solid elemental sulphur precipitates. In the next step, bacteria convert the ferrous ions back to ferric ions through reaction 2, after which the final, solid copper is recovered through half-reaction 3 :
CuFeS₂(s) + Fe³⁺ → Cu²⁺ + Fe²⁺ + S(s) reaction 1
Fe²⁺ + 0₂ + H⁺ → Fe³⁺ + H₂0 reaction 2
Cu²⁺ + 2e⁻¹ → Cu(s), half - reaction 3
The Escondida mine in Chile produces 7.5 x 10⁹ kg of solid copper per year through half - reaction 3, which has a yield of 97 % . If reaction 1 has a yield of 73% and reaction 2 a yield of 100%, calculate the mass of solid sulphur that precipitates per year at this mine as a result of copper mining.