A5.00 g mixture of methane (ch4) and ethane (c2h6) is combusted in oxygen gas to produce carbon dioxide and water. if 14.09 g of co2 is produced, how many grams of methane was in the original 5.00 g mixture ?

We have two unknowns for this problem. These are the amount of Ch4 and the amount of C2H6. We let these as x and y respectively. It should be that we generate two equation in order to solve this problem. We do as follows:

Equation 1:
x + y = 5

Equation 2
CO2 produced from CH4 + CO2 produced from C2H6 = 14.09
x(44.01/16.05) + y(4)(44.01)/(2)(30.08) = 14.09
2.74x +2.93y = 14.09

Solving simultaneously,
x = 2.95 g CH4
y= 2.05 g C2H6