Question

how the induced orientation, and dispersion interactions trend between HCl, HBr, and HI. Why do the dispersion interactions increase from HCl to HI? Why do the orientation interactions decrease from HCl to HI? Why are induced interactions greatest in HCl and lowest in HI?

Answer 1

dispersion interactions

HCl < HBr < HI

dispersion interaction increases with increase in molar mass. HI molar mass is high so its dispersion forces are high

orientaion interactions :

among Cl, Br , I ions Cl- ion size is smaller . so it can hold good hydrogen and properly orientated. but in case HI , iodine size is bigger so it cannot hold good hydrogen. so there is no proper orientation.

so orientation interactions order : HCl > HBr > HI

induced interactions :

Cl electronegativity is higher than the Br and I . so there are greater dipole moment between H and Cl. so in HCl , the bond between H and Cl is more polar . so greater induced interactions are present in HCl .

when electronegativity decreases induced interactions also decreases.