In a Hall-Heroult cell $2.70 kg$ of aluminium ( $Al = 27$ ) is produced. Taking $F = 96500 C/mol$ , $C = 12$ and $22.4 L/mol$ at STP, select the correct statement(s).

AThe charge passed is $2.895 e + 07 C$
BIf the anode gas were entirely $CO X_{2}$ , the mass of carbon burnt would be 900 g
CIf an inert anode liberated only $O X_{2}$ , its volume at STP would be 1680 L
DIf the anode gas were entirely $CO$ , the mass of carbon burnt would be 900 g

Answer: A, B, C

Moles of Al

= 100

, each needing 3 mol of electrons, so

Q = 300 \times 96500 = 2.895 e + 07 C

(true). Forming

CO X_{2}

takes 4 mol of electrons per C, so C

= 300/4 = 75

mol

= 900 g

(true). Forming

CO

takes 2 mol electrons per C, giving 150 mol

= 1800 g

, not 900 g (statement 3 false). Oxygen is

300/4 = 75

mol

= 1680 L

(true).