Form the equation for the complete burning of C3H8
Firstly, note that the reaction is complete burning. This means there is no carbon monoxide produce, only carbon dioxide.Secondly, we should know that all simple combustion reactions produce water.So, we know on the Left Hand Side (LHS) of the equation is: C3H8 as this is a reactant. We also know that oxygen must be present in order for combustion. So we know: C3H8 + O2 -> CO2 + H2O However, this equation is not balanced as there is more carbon atoms on the LHS than the RHS. Hence a stoichiometric balance is needed.Choose an atom first to balance (I always start with carbon) so:C3H8 + O2 -> 3CO2 + H2O now LHS carbon = 3 and RHS carbon =3 - it's balanced in carbon. Now choose another atom, here you should hydrogen because the oxygen on the LHS can be used easily to balance at the end, whereas hydrogen is connected to other atoms. So:C2H8 + O2 -> 3CO2 + 4H2O now LHS hydrogen = 8 and RHS hydrogen = 4 * 2 = 8 - it's balanced. Now to count the RHS oxygen to balance on the LHS: (32) + (41) = 10. So, since it is O2 on the LHS, we can do 10/2 = 5, giving our balanced equation:C2H8 + 5O2 -> 3CO2 + 4H2O and don't forget state symbols! So: C2H8 (g) + 5O2 (g) -> 3CO2 (g) + 4H2O (g)
