Question

what volume of oxygen at STP is required to affect the combustiom of 11 litres of ethylene [C2H4] at 273° c and 380 mm of hg prssure?

C2H4+3O2----» 2CO2+2H2O

Answer 1

Let no. of mole of C2H4 be n
P = 380/760 atm = 1/2 atm
T = 273+273 = 546K
V = 11 L
R = 0.0821
By applying PV = nRT,we get ;

11/2= n*0.0821*546
=> n = 0.123 mole

O2 required for combustion of one mole of C2H4 = 3mole
=>0.123 mole = 3*0.123 mole  O2 required
                = 0.369mole
We know that,volume of one mole of gas at stp = 22.4L
=>Volume of 0.369 mole O2 at stp = 22.4*0.369 = 8.27L = 9L

Hope it helps!