[ChmNerd111]

A 1.0 L sample contains a mixture of CH4 (g) and C2H2 (g) at 0 degrees C and 1 atm. When the sample is completely combusted, it releases 43.6 kJ of heat. Determine the percent composition of the sample by volume.

To start, I used the ideal gas law to find the total number of moles (CH4 + C2H2). Then, I know that the total heat released (43.6 kJ) is equal to the sum of the heats of CH4 and C2H2. But when I go to calculate the delta H for CH4 and then for C2H2, i get stuck because i have one equation and two unknowns. I tried doing it algebraically (with just the one equation and made it only one unknown) and set CH4 equal to, lets say, X, and then set C2H2 to 43.6-X, but got the wrong answer. Any suggestions?

[Borek]

There are two equations - one is for amount of heat other is for volume.