Rationalize the difference in boiling points between the members of the following pairs of substances. Part APart complete HF (2
0 ∘C) and HCl (-85 ∘C) (20 ) and (-85 ) HF has the higher boiling point because HF molecules are more polar. HF has the higher boiling point because hydrogen bonding is weaker than dipole-dipole forces. HF has the higher boiling point because hydrogen bonding is stronger than dipole-dipole forces. HF has the higher boiling point because of ionic bonding. Previous Answers Correct HF has a much higher boiling point than HCl, indicating that it contains strong intermolecular forces. Specifically, it contains hydrogen bonding, which is a stronger force than dipole-dipole forces. Part B CHCl3 (61 ∘C) and CHBr3 (150 ∘C) (61 ) and (150 ) CHCl3 has the
HF has the higher boiling point because HF molecules are more polar. Part B: CHBr3 molecules possess stronger intermolecular interaction due to higher molar mass than CHCl3
Explanation:
Fluorine is more electronegative than chlorine. This implies that HF is more polar and possess stronger hydrogen bonds than HCl molecules.
In part B, the magnitude of dispersion forces depend on molar mass, the greater the molar mass, the greater the magnitude of dispersion forces between molecules, hence CHBr3 has a greater boiling point than CHCl3
The strength of a covalent bond is measured by its bond dissociation energy, that is, the amount of energy required to break that particular bond in a mole of molecules. The enthalpy of a reaction can be estimated based on the energy input required to break bonds and the energy released when new bonds are formed.
