the number in the answer box is NOT correct.

ST2F1 and ST2F2- A liquid alkane CnH2n+2 has a standard enthalpy of vaporization at room temperature given approximately by (5n+1.5) kJ/mol. The standard enthalpy of vaporization of water at room temperature is 44.01 kJ/mol. Estimate the standard enthalpy of combustion (in kJ/mol] of the liquid 15-carbon alkane using the enthalpy of vaporization given above and the mean bond energies below (except for CO2 where you should use the precise value of 799 kJ/mol). Obviously you first must write a balanced chemical equation for the combustion reaction. Don't neglect to consider the states of matter and any necessary phase changes in the enthalpy calculation. Because I ask you to use bond enthalpies your answer will not quite match the experimental value if you bother to search for it. C-C 348 kJ/mol C-H 412 kJ/mol O=O 497 kJ/mol C=O 799 kJ/mol (in CO2) but otherwise 743 kJ/mol on average O-H 463 kJ/mol -8,518.34