From the following data
`CH_(3)OH(l)+(3)/(2)O_(2)(g) rarr CO_(2)(g) +2H_(2)O(l)`
`Delta_(r) H^(@)=-726 kJ mol^(-1)`
`H_(2)(g)+(1)/(2)O_(2)(g) rarr H_(2)O(l), Delta _(r) H^(@)=-286 kJ mol^(-1)`
`C("graphite") +O_(2)(g) rarr CO_(2)(g), Delta _(r) H^(@)=-393 kJ mol^(-1)`
The standard enthalpy of formation of `CH_(3)OH(l)" in "kJ mol^(-1)` is

Explanation

Given `triangle_(f)H^@ (CO_(2))="-393 KJ mol"^(-1)`
`triangle_(f)H^@ (H_(2)O_(1))="-286 KJ mol"^(-1)`
`CH_(3) OH_(l) +3/2 O_(2(g)) to CO_(2(g)) +2H_(2)O_(l) triangleH_(r)^0="-726 KJ mol"^(-1)`
`underset("reactants")(triangle_(f)H^0 CH_(3)OH+(O)) to underset("products")(triangle_(f)H^@ (CO_(2))+2 triangle_(f) H_(H_(2)O_(l))^(@)`
`triangle_(r)H^@=-726 KJ mol^(-1)`
`triangle_(f)H^@=triangleH_("total")^@` of the products `-triangleH_("total")^@` of the reactants
`-726=[-393 +2(-286)] -[triangle_(f)H^@ CH_(3)OH]`
`triangle_(f)H^@ (CH_(3)OH)=726+[-393+2(-286)]"KJ mol"^(-1)`
`=-239" KJ mol"^(-1)`