If the bond dissociation energies of XY , X_(2) and Y_(2) ( alldiatomic molecules )are in the ratio1:1 : 0.5 and DeltaH _(f)for the formation of XY of - 200 kJ mol^(-1) , the bond dissociation energy of X_(2) will be

If the bond dissociation energies of XY , X_(2) and Y_(2) ( alldiatomi

1.	If the bond dissociation energies of XY , X_(2) and Y_(2) ( alldiatomic molecules )are in the ratio1:1 : 0.5 and DeltaH _(f)for the formation of XY of - 200 kJ mol^(-1) , the bond dissociation energy of X_(2) will be
Answer» `100 kJ mol^(-1)` `200 kJ mol^(-1)` ` 400 kJ mol^(-1)` ` 800 kJmol^(-1)` Solution :Suppose BOND dissociation energy of XY `=akJ mol^(-1) , i.e., `BE (XY )= a . Then BE `9X_(2)0= a, BE(Y_(2))= 0.5 a` Aim `:(1)/(2) X_(2)+ (1)/(2) Y_(2) rarr XY` `Delta_(r)H = BE` ( Reactants ) - BE ( Products ) `= [ (1)/(2) BE (X_(2)) + (1)/(2) BE(Y_(2)) ] = BE(XY)` `:.- 200 =((a)/(2) + (0.5a)/( 2)) -a` or` - 200 = - 0.25 a` or `a= 800 kJ mol^(-1)`