Question

What volume of Oxygen at STP is required to affect the combustion of 11 litres of ethylene [$C_{2} H_{4}$] at 273 degree C and 380 mm of Hg pressure?$C_{2} H_{4} 3O_{2} --\ \textgreater \ 2 CO_{2} 2 H_{2} O$

Answer 1

volume at 273 degree C and 380 mm of Hg pressure = 11 l
volume at 273 degree C and 750 mm of Hg pressure = x l

P1V1 = P2V2
380*11 = 760*x
x = 380*11/750 = 5.6 liters
volume at stp = 5.6ltrs

no.of moles = 22.4/5.6 = 0.25 moles
1 mole of ethylene uses = 3 mole of oxygen
0.25 mole of ethylene uses = 3*0.25 = 0.75 mole of oxygen

Volume if 0.75 mole oxygen at stp = 0.75*22.4 = 16.8 litres