the balanced equation for the combustion reaction is as follows
2C₃H₇OH + 9O₂ ---> 6CO₂ + 8H₂O
we are assuming that O₂ is in excess and C₃H₇OH is the limiting reactant
therefore the amount of product formed depends on the amount of C₃H₇OH present.
we have to find the number of CO₂ and H₂O moles formed
molar ratio of C₃H₇OH to CO₂ is 2:6 simplified to 1:3
when 1 mol of C₃H₇OH reacts - 3 mol of CO₂ is formed
therefore when 3.40 mol of C₃H₇OH reacts - 3 x 3.40 = 10.2 mol of CO₂ is formed
molar ratio of C₃H₇OH to H₂O is 2:8 simplified to 1:4
when 1 mol of C₃H₇OH reacts - 4 mol of H₂O is formed
therefore when 3.40 mol of C₃H₇OH reacts - 4 x 3.40 = 13.6 mol of H₂O is formed
10.2 mol of CO₂ and 13.6 mol of H₂O is formed