When 2.5 liters of oxygen gas reacts with excess methane how many liters of carbon dioxide is produced?
Given equal pressures and common temperatures, equal volumes of gases contain an equal number molecules. The stoichiometry of the combustion reaction demands that there is TWICE the molar quantity of dioxygen to methane, and thus twice the volume.
Of course, under these conditions of limited oxidant, incomplete combustion of methane to carbon monoxide or carbon as soot may occur. How would you represent this reaction?