The bond dissociation energies of X 2   Y 2 and XY are in the ratio of 1   : 0 .5   : 1 .   ΔH for the formation of XY is - 200   kJ   mol - 1 . What will be the bond dissociation energy of X 2 ?

Step-by-step solution

Let B.E. of x 2 ,   y 2 and xy are x   kJ   mol - 1 ,   0 .5 x   kJ   mol - 1 and x   kJ   mol - 1 respectively 1 2 X 2 + 1 2 Y 2 → XY ;   ΔH = - 200   kJ   mol - 1 ΔH = - 200 = Σ B . E Reactant - Σ B . E Product - 200 = 1 2 × x + 1 2 × 0 .5 x - 1 × x ⇒ x = 800 kJ    mol B.E of X 2 = 800   kJ   mol - 1