When 3.05 moles of ch4 are mixed with 5.03 moles of 02 the limiting reactant is?

To determine the limiting reactant of a reaction, it is important first to know the balanced reaction. For this case, it is:

CH4 + 2O2 = CO2 + 2H2O

We determine as follows:

3.05 mol CH4 (2 mol O2 / 1 mol CH4) = 6.1 mol O2 needed

5.03 mol O2 (1 mol CH4 / 2 mol O2) = 2.515 mol CH4 needed

Since the needed amount of CH4 is less than what is given, the O2 should be the limiting reactant since it would react completely.