How many moles of co2 are produced when 5.20 mol of ethane are burned in an excess of oxygen?

2C2H6 + 7O2 = 4CO2 + 6H2O

According to the equation of the reaction of ethane combustion, ethane and carbon dioxide have following stoichiometric ratio:

n(C2H6) : n(CO2) = 1 : 2

n(CO2) = 2 x n(C2H6) 

n(CO2) = 2 x 5.2 = 10.4 mole of CO2 is formed