Compare a sample of HBr to a sample of HCl. The electronegativity difference between H and Cl is 0.9. Which would exhibit stronger dipole-dipole interactions, HBr or HCl? Explain why.

Answer 1

The dipole moment for HBr is 0.80 D (D = Debye units)
The dipolemomnt for HCl is 1.08 D.
Therefore I would think HCl would exhibit strong dipole-dipole interactions. The electronegativity difference between H and Br is about 0.8 and that gives the same answer. I assume one is comparing HCl gas with HBr gas. Mixing with H2O ushers in another dipole and that complicates things as well have different concentrations too.