Question
Arrange the following:
H–H, D–D and F–F in order of increasing bond dissociation enthalpy.
Solution
Bond dissociation enthalpy. The order of increasing bond dissociation enthalpy is:
F-F<H-H<D-D
Reason: Since D has a smaller size than H, therefore D-D bond has the highest bond dissociation enthalpy followed by H – H. On the other hand, F – F bond has minimum dissociation enthalpy because of repulsion between lone pairs of F and bond pair.
Hence the bond dissociation enthalpy increases in the order F-F<H-H<D-D
F-F<H-H<D-D
Reason: Since D has a smaller size than H, therefore D-D bond has the highest bond dissociation enthalpy followed by H – H. On the other hand, F – F bond has minimum dissociation enthalpy because of repulsion between lone pairs of F and bond pair.
Hence the bond dissociation enthalpy increases in the order F-F<H-H<D-D
