The enthalpies of formation of each of the compound involved in the chemical reaction presented above are given below:
CO2: -393.5 kJ/mol CO: -99 kJ/mol O2: 0 kJ/mol
As observed O2 will not have enthalpy of formation as it is a pure substance.
To calculate for the enthalpy of reaction, enthalpy of formation of products - enthalpy of formation of reactants = (-99 kJ/mol) - (-393.5 kJ/mol) = 294.5 kJ/mol
It all depends what theory it is most are supported by really good evidence but they just don't have all the evidence so it can't be proven a fact at that time
