Copper(I) sulphide is converted to copper in two stages: 2Cu2S + 3O2 -> 2Cu2O + 2SO2, then 2Cu2O + Cu2S -> 6Cu + SO2 (no further air). Taking all the Cu2S through both stages in the correct proportion, the volume of O2 at STP needed to obtain 127 kg of copper (Cu = 63.5) is

JEE Advanced levelSingle correct optionDifficulty 3 of 3mt100

Copper(I) sulphide is converted to copper in two stages: $2 Cu X_{2} S + 3 O X_{2} 2 Cu X_{2} O + 2 SO X_{2}$ , then $2 Cu X_{2} O + Cu X_{2} S 6 Cu + SO X_{2}$ (no further air). Taking all the $Cu X_{2} S$ through both stages in the correct proportion, the volume of $O X_{2}$ at STP needed to obtain $127 kg$ of copper (Cu = 63.5) is

Adding the stages (2 mol

Cu X_{2} S

oxidised in stage 1 for every 1 mol in stage 2) gives the overall

3 Cu X_{2} S + 3 O X_{2} 6 Cu + 3 SO X_{2}

. So 6 mol Cu need 3 mol

O X_{2}

, i.e. 0.5 mol

O X_{2}

per mol Cu.

127 kg

= 2000

mol, so

O X_{2} = 1000

mol

= 22400

= 22.4 m^{3}