Considering the molecular mass and polarity influences on physical properties,which of the following predictions about the boiling points of elemental bromine and chlorine fluoride is most apt to be correct?

Question

Quizplus · Accepted Answer

Bromine (Br2) has a higher molecular mass (159.8 g/mol) than chlorine fluoride (ClF, 54.5 g/mol). According to the general rule, substances with higher molecular mass tend to have higher boiling points, so Br2 would be expected to have a higher boiling point than ClF.

However, polarity also affects the boiling point. ClF is a polar molecule due to the electronegativity difference between chlorine and fluorine atoms, which creates a dipole moment in the Cl-F bond. Bromine, on the other hand, is a nonpolar molecule because the two bromine atoms share electrons equally in the bond.

Polar substances experience stronger intermolecular forces due to the attraction between the dipoles. Therefore, ClF is expected to have a higher boiling point than Br2 despite its lower molecular mass.

Therefore, the option that best predicts the boiling points of these substances is (D) Molecular mass predicts Br2 has the higher boiling point, but molecular polarity predicts ClF has the higher boiling point.

Considering the Molecular Mass and Polarity Influences on Physical Properties,which