## Chemistry and Chemical Reactivity (9th Edition)

$+103.61\ kJ/mol$
Enthalpies of formation (kJ/mol): $H_2O(l):-285.83, CO_2(g):393.509$ Enthalpy of combustion: $-4395.0=4\times-285.83+8\times-393.509-x$ $x=+103.61\ kJ/mol$, which is the enthalpy of formation of styrene.