CHEMISTRY: URGENT
posted by LC .
24cm^3 of a mixture of methane and ethane were exploded with 90cm^3 of oxygen. After cooling to RTP the volume of gases was noted and it decreased by 32cm^3 when treated with KOH. Calculate the composition of the mixture.

CH4 + 2O2 ==> CO2 + 2H2O
2C2H6 + 7O2 ==> 4CO2 + 6H2O
I would look at this. Since we have all gases we need not convert to mols but we can use volume directly.
Let x = volume CH4
and y = volume C2H6

x + y = 24 cc which is equation 1.
x cc of CH4 will produce x cc of CO2.
y cc of C2H6 will produce 4y/2 = 2y CO2 so equation 2 is
x + 2y = 32. Solve those two equations simultaneously for cc x and cc y. 
Thank you DrBobb22