The change in internal energy in different steps of the process `A to B to C to D ` are given: `A toB,x*kJ*mol^(-1),BtoC,-ykJ*mol^(-1),CtoD,zkJ*mol^(-1)`. What will the value of `DeltaU` be for the change `A to D`?

Explanation

`A overset(DeltaU_(1))toBoverset(DeltaU_(2))to C overset(DeltaU_(3))toD`
`DeltaU_(1)=U_(B)-U_(A)=xkJ*mol^(-1)`,
`DeltaU_(2)=U_(C)-U_(B)=-ykJ*mol^(-1)`
`DeltaU_(3)=U_(D)-U_(C)=zkJ*mol^(-1)`
`therefore`For the change `AtoD`,
`DeltaU=U_(D)-U_(A)=(U_(D)-U_(C))+(U_(C)-U_(B))+(U_(B)-U_(A))`
`=(z-y+x)kJ*mol^(-1)`.