Final answer:
In the chemical reaction CH4 + 2O2 → CO2 + 2H2O with 2.0 moles of CH4 and 2.0 moles of O2, there are no excess reactants. The given amount of O2 is the limiting reactant, and it will be completely consumed when reacting with the CH4.
Step-by-step explanation:
Given the equation CH4 + 2O2 → CO2 + 2H2O, when 2.0 moles of CH4 are reacted with 2.0 moles of O2, we want to know which reactant is in excess. The appropriate stoichiometric ratio for this reaction is 1 mole of CH4 to 2 moles of O2. Therefore, 2.0 moles of CH4 would ideally require 4.0 moles of O2 to react completely.
Since only 2.0 moles of O2 are provided, O2 is the limiting reactant and all of it will be consumed. No excess reactants will remain because the moles of CH4 are provided in the exact stoichiometric ratio needed to react with the moles of O2 available.