Question

Which process could be used to calculate the bond energy for the covalent bond X-Y by dividing
its ∆H by n?
A XYn(g) → X(g) + nY(g)
B 2XYn (g) → 2XYn-1(g) + Y2(g)
C Y(g) + XYn-1(g) → XYn(g)
D nXY(g) → nX(g) + n/2 Y2(g)

Answer 1

Remember what bond energy is,it is the energy released when a covalent bond of a gaseous molecule is broken to give gaseous atoms and not molecules or compounds or molecules. So in A only is this happening in the rest of the options ∆H not only contains the bond breaking energy but also bond formation so the resulting ∆H for B,C and D is lesser than the value of X----Y bond energy !