chemistry stoichiometry question

Question

if 2.10 moles of propane (C3Hg) react with excess oxygen in a complete combustion reaction, how many moles of water are produced?

Answer 1

To determine the number of moles produced, first generate a balanced equation for the reaction

C₃H₈ + O₂ --> CO₂ +H₂O

First balance Carbon and then the other elements

C₃H₈ + O₂ --> 3CO₂ + H₂O (carbon balanced)

C₃H₈ + O₂ --> 3CO₂ + 4H₂O (carbon and hydrogen balanced)

C₃H₈ + 5O₂ --> 3CO₂ + 4H₂O (all elements balanced)

The balanced equation gives the proper mole ratios for a complete reaction, thus one mole of propane produces 4 moles of steam after complete combustion. Therefore 2.10 moles of propane would produce 2.10 times 4 = 8.40 moles of steam.