During the combustion of ethane, C2H6(g), 40.4 grams of liquid are collected . How many liters of ethane, measured at 3.55 atm and 33 C, were burned?

Answer 1

Here is a link that will solve most stoichiometry problems.
http://www.jiskha.com/science/chemistry/stoichiometry.html
Use the above to calculate the grams ethane used the use PV = nRT to solve for volume ethane. The liquid to which they refer to is water from the following:
2C2H6 + 7O2 ==> 4CO2 + 6H2O
Post your work if you get stuck.