The enthalpy change in a process is the same, whether the process is carried out in a single step or inseveral steps.
a) Identify tha law stated here.
b) Calculate the enthalpy of formation of `CH_4` from the following data :
i) `C_((s))+O_(2(g))rightarrowCO_(2(g))`
`DeltaH` = -393.7kJ/mol
ii) `H_(2(g))+frac{1}{2}O_(2(g))rightarrowH_2O_((l))`
`DeltaH` = -285.8kJ/mol
iii) `CH_(4(g))+2O_(2(g))rightarrowCO_(2(g))`
`DeltaH`=-890.4kJ/mol