Which substance ( HBr or HF ) has the higher boiling point?
Its HF but chose one of the most appropriate reason.
1. Both substances are nonpolar but the higher boiling includes hydrogen bonding 2. Both substances are nonpolar but the higher boiling is more polarizable
3. The higher boiling substance is polar and the other is not
4. The lower boiling substance is polar and the other is not
5. The higher boiling substance has smaller vander Waals forces than the lower boiling
6. The higher boiling substance has greater vander Waals forces than the lower boiling
7. The higher boiling substance is ionic and the other is not
8. The lower boiling substance is ionic and the other is not
9. The higher boiling substance has hydrogen bonds and the other does not 10. The lower boiling substance has hydrogen bonds and the other does not 11. Both substances are ionic but the higher boiling has a larger cohesive energy
12. Both substances are ionic but the lower boiling has a larger cohesive energy
13. The higher boiling substance is ionic and the other is not. Ionic bonds are stronger than hydrogen bonds
14. The lower boiling substance is ionic and the other is not. Ionic bonds are weaker than hydrogen bonds
15. The higher boiling substance is ionic and the other is not. Ionic bonds are stronger than vander Waals forces
16.The lower boiling substance is ionic and the other is not. Ionic bonds are weaker than vander Waals forces
Most of these statements are not true. #5 is true but not the reason I would choose. I would pick 9.
thnx you are correct
The most appropriate reason for HF having a higher boiling point than HBr is option 9: "The higher boiling substance has hydrogen bonds and the other does not."
To explain why this is the case, we need to understand the nature of the molecular interactions involved. Both HBr and HF are composed of polar covalent bonds since there is a significant electronegativity difference between hydrogen and the halogen atoms (bromine or fluorine). However, HF has a higher boiling point due to the presence of hydrogen bonding.
Hydrogen bonding occurs when a hydrogen atom is bonded directly to a highly electronegative atom (in this case, fluorine). The fluorine atom attracts the bonding electron pair more strongly, resulting in a partial positive charge on the hydrogen atom. This partial positive charge can then interact with another highly electronegative atom in a neighboring molecule, creating a hydrogen bond.
The presence of hydrogen bonds in HF molecules leads to stronger intermolecular forces compared to the only van der Waals forces present in HBr molecules. Van der Waals forces, also known as London dispersion forces, are relatively weaker compared to hydrogen bonding.
As a result, HF molecules are more strongly attracted to each other through hydrogen bonding, requiring more energy to break these bonds and convert the substance from a liquid to a gas during boiling. In contrast, HBr molecules have weaker intermolecular forces, resulting in a lower boiling point.
Therefore, the higher boiling point of HF compared to HBr is due to the presence of hydrogen bonding in HF, which results in stronger intermolecular forces.