Compléter COMBUSTION OF HYDROCARBONS CCM (D) (D)Version en ligne Combustions where the chemical equation is balanced and the types of combustion is identified. par Dieggoxxe GG 1 The formula for methane gas is , which is one of the components of natural gas ; constituting up to 80% of the gas mixture . Another gas that constitutes natural gas is propane , whose combustion reaction is as follows : C3H8 + O2 - - - - - > CO2 + H2O + Energy . Therefore , a complete combustion is carried out , which is characterized by a blue flame . This fuel comes from petroleum , but it must be separated by fractional distillation in oil refineries . Another used fuel is heptane . When it is combusted in low oxygen conditions , the following reaction takes place : C7H16 + O2 - - - - - > CO + H2O . In this reaction , a yellow flame is observed , which is characteristic of an incomplete combustion . Another example would be the combustion of heptadecane : C17H36 + O2 - - - - - > C + H2O . Due to the obtained by - products , we can observe that it is an incomplete combustion and it is evident that little energy will emanate . Finally , chemists are investigating the use of nonane as a fuel for internal combustion motor vehicles , whose complete combustion is : C9H20 + O2 - - - - - > CO2 + H2O , from which a large amount of energy is obtained .