the boiling point of HF is 1. higher than, 2. lower than, 3. similar to the boiling point of H2 , and it is 1. higher than , 2. lower than , 3. similar to the boiling point of N2
The Correct Answer and Explanation is :
The boiling point of hydrogen fluoride (HF) is higher than the boiling point of hydrogen (H₂) and higher than the boiling point of nitrogen (N₂).
Explanation:
Boiling points are influenced by intermolecular forces, molecular weight, and molecular structure. Let’s examine HF, H₂, and N₂.
- Hydrogen Fluoride (HF):
HF has a high boiling point compared to H₂ and N₂ because of hydrogen bonding. Hydrogen bonding is a particularly strong type of dipole-dipole interaction that occurs when hydrogen is bonded to highly electronegative atoms like fluorine, oxygen, or nitrogen. In HF, the fluorine atom is very electronegative, creating a strong dipole moment. This leads to significant hydrogen bonding between HF molecules, requiring more energy to break these bonds and transition the substance from liquid to gas. HF has a boiling point of around 19.5°C (67.1°F). - Hydrogen (H₂):
Hydrogen molecules are non-polar, meaning they exhibit only weak van der Waals forces (London dispersion forces). These are the weakest intermolecular forces, leading to very low boiling points. H₂ has a boiling point of around -252.9°C (-423.2°F). The lack of strong intermolecular forces makes it easy to vaporize, giving it a boiling point much lower than HF. - Nitrogen (N₂):
Nitrogen, like hydrogen, is non-polar and experiences weak van der Waals forces. It has a boiling point of about -195.8°C (-320.4°F), which is also significantly lower than HF’s boiling point. Though nitrogen molecules are larger than hydrogen molecules, their non-polar nature and lack of hydrogen bonding result in a relatively low boiling point.
Summary:
- HF has a higher boiling point than both H₂ and N₂ due to the strong hydrogen bonding present in HF, whereas H₂ and N₂ exhibit only weak van der Waals forces.