Fill in the Blanks 4. Combustion CCM ENGOnline version Combustion where balancing equations is needed as well as identifying if it is complete or incomplete by Clara Marcelín 1 Methane gas has a formula of . It is one fo the main components of natural gas , composing 80% of it . Other molecule that is also part of natural gas is propane , which has the following combustion reaction C3H8 + O2 - - - - - > CO2 + H2O + Energy . This is a complete combustion reaction , characterized by a flame . This fuel comes from oil but must be separated first by fractional distillation on refineries . Another important fuel is heptane , which when there is a lack of oxygen undergoes the following reaction C7H16 + / O2 - - - - - > CO + H2O . This reaction is an combustion characterized by a flame Another example would be the combustion of heptadecane with the following formula C17H36 + O2 - - - - - > C + H2O . By looking at the byproducts we can see that it is an combustion and will produce low amounts of . Finally , chemists are researching the use of nonane as a fuel for internal combustion engines with a a chemical reaction as follows C9H20 + O2 - - - - - > CO2 + H2O . This reaction produces big amounts of