The equation
C (graphite) `+O_(2)(g) CO_(2)(g)`
`Delta H=-395.5kJ`
can be reversed as
`CO_(2)(g) rarr ` C ("graphite")+O_(2)` gas
`DeltaH= +395.5 kJ`
This is called as

C_("graphite") + O_(2(g)) : Delta H = -393.5 kJ . Delta H of the above reaction cannot be

C _((s)) + O _(2 (g)) to CO _(2(g)) ,Delta H =-393.5kJ. This equation can not represent

With the help of a thermochemical equation, calculate Delta_(f)H^(@) at 298 K for the following reactions : "C(graphite)" + O_(2)(g) rarr CO_(2)(g) , Delta H = -393.5 kJ//mol H_(2)(g) + (1)/(2)O_(2)(g) rarr H_(2)O(l) , Delta_(f)H^(@) = -285.8 kJ//mol CO_(2)(g) + 2H_(2)O(l) rarr CH_(4)(g) + 2O_(2)(g) , Delta_(f)H^(@) = +890.3 kJ//mol

Calculate DeltaH in Joules for C_(("graphite")) rarr C_(("Diamond")) by using the following data C_(("graphiter")) + O_(2(g)) rarr CO_(2(g)) , DeltaH^@ =-393.5KJ C_(("Diamond")) + O_(2(g)) rarr CO_(2(g)) , DeltaH^@ =-395.4KJ