Question

The most common source of copper (Cu) is the mineral chalcopyrite (CuFeS2). How many kilograms of chalcopyrite must be mined to obtain 210. g of pure Cu?

Answer 1

The molecular weight of chalcopyrite is equivalent to 183.53 grams which is made up of copper 63.56 g, iron 55.85 g and sulphur 64.12 g for a total of 183.53 g and so copper is 63.56/183.53=34.63%. So then, kg chalcopyrite x 0.3463=210 g or 0.21 kg pure Cu so kg chalco = 0.21/0.3463=0.606 kg chalcopyrite.

Answer 2

To find out the answer, we must know the mass percentage of Cu in the mineral chalcopyrite.

Mass percentage of Cu = molar mass of Cu/molar mass of chalcopyrite = 64/(64+56+32*2) = 34.8%.

So to obtain 210 g pure Cu, the amount of mineral need = mass of Cu/mass percentage of Cu = 210 g/34.8% = 603 g = 0.603 kg.