Change in enthalpy in different steps of the process `A to B to CtoA` are given: `AtoB,xkJ*mol^(-1),CtoA,ykJ*mol^(-1)`. Find the value of `DeltaH` for the step `BtoC`.

Explanation

The initial and final states (A) are same in the given process. So it is a cyclic process. Since H is a state function, `DeltaH=0` for the process. Thus in this process,
`DeltaH=(H_(B)-H_(A))+(H_(C)_H_(B))+(H_(A)+H_(C))=0`
or, `x+(H_(C)-H_(B))+y=0 or, (H_(C)-H_(B))-(x+y)kJ*mol^(-1)`
So, change in enthalpy for `BtoC=-(x+y)kJ*mol^(-1)`