Entalphy of formation

[nihantokar]

i keep finding the answer positive but is the answer negative because it should be an exothermic reaction?

[DariusDuhan]

Yes, a combustion reaction is always exothermic, so we see a negative change in enthalpy.

You can calculate the change in enthalpy or enthalpy of formation using this equation:

Change in enthalpy = Total Enthalpy of Reactants - Total Enthalpy of Products