[toddkennedy]

Can someone help me with this?

"A mixture of CH4(g) and C2H6(g) has a total pressure of 0.53 atm.  Just enough O2(g) is added to the mixture to bring about its complete combustion to CO2(g) and H2O(g). The total pressure of the two product gases is found to be 2.2 atm. Assuming constant volume and temperature, find the mole fraction of CH4 in the mixture."

I would think that the partial pressure of CH4 added to the partial pressure of C2H6 would equal 0.53 atm, but I'm not even sure about that.  After that, I have no idea how to solve for anything.

[AWK]

Write down a balanced combustion reaction (separately!).
Note, at these conditions moles are proportional to pressures, water are gaseous, and the ideal gas law is assumed to hold.

[Padfoot]

Initial amounts can be related to initial pressure.
Initial amounts can be related to final pressure (through products formed)