Consider the substances hydrogen [tex]\(\left( H_2 \right)\)[/tex], fluorine [tex]\(\left( F_2 \right)\)[/tex], and hydrogen fluoride [tex]\(\left( HF \right)\)[/tex]. Based on their molecular structures, how does the boiling point of [tex]\(\text{HF}\)[/tex] compare with the boiling points of [tex]\(\text{H}_2\)[/tex] and [tex]\(\text{F}_2\)[/tex]?
The boiling point of [tex]\(\text{HF}\)[/tex] is [tex]\(\square\)[/tex] the boiling point of [tex]\(\text{H}_2\)[/tex], and it is [tex]\(\square\)[/tex] the boiling point of [tex]\(\text{F}_2\)[/tex].
Select the correct answer from each drop-down menu: - The boiling point of [tex]\(\text{HF}\)[/tex] is [tex]\(\square\)[/tex] the boiling point of [tex]\(\text{H}_2\)[/tex]. - The boiling point of [tex]\(\text{HF}\)[/tex] is [tex]\(\square\)[/tex] the boiling point of [tex]\(\text{F}_2\)[/tex].
To understand how the boiling points of [tex]\( \text{H}_2 \)[/tex], [tex]\( \text{F}_2 \)[/tex], and HF compare, we need to consider their molecular structures and the intermolecular forces involved.
1. Molecular Structure & Intermolecular Forces: - [tex]\( \text{H}_2 \)[/tex]: Hydrogen molecule is nonpolar and experiences weak London dispersion forces. - [tex]\( \text{F}_2 \)[/tex]: Fluorine molecule is also nonpolar and similarly experiences weak London dispersion forces. - HF: Hydrogen fluoride is a polar molecule. Due to the significant electronegativity difference between hydrogen (H) and fluorine (F), HF molecules experience strong hydrogen bonding, a much stronger intermolecular force compared to the London dispersion forces in [tex]\( \text{H}_2 \)[/tex] and [tex]\( \text{F}_2 \)[/tex].
2. Boiling Points: - The boiling point of a substance is higher when the intermolecular forces are stronger because more energy is required to separate the molecules into a gaseous state. - As HF experiences strong hydrogen bonding, it will have a higher boiling point. - Both [tex]\( \text{H}_2 \)[/tex] and [tex]\( \text{F}_2 \)[/tex] are nonpolar and only have weak London dispersion forces, resulting in lower boiling points.
3. Comparison: - The boiling point of HF ([tex]\(\text{hydrogen fluoride}\)[/tex]) is higher than the boiling point of [tex]\( \text{H}_2 \)[/tex] (hydrogen) due to the presence of strong hydrogen bonds in HF. - Similarly, the boiling point of HF is higher than the boiling point of [tex]\( \text{F}_2 \)[/tex] (fluorine) for the same reason.
Therefore, based on the intermolecular forces and molecular structures:
The boiling point of HF is higher than the boiling point of [tex]\( \text{H}_2 \)[/tex], and it is higher than the boiling point of [tex]\( \text{F}_2 \)[/tex].
