Question

Why $\mathrm{HI}$ has a higher boiling point than $\mathrm{HCl}$?

Answer 1

$\mathrm{HI}$ and $\mathrm{HCl}$:

• Hydroiodic acid $\mathrm{HI}$ is a hydrogen iodide aqueous solution. It's a powerful acid that's totally ionized in an aqueous solution.
• It has no color. Concentrated solutions normally have an HI of 48 to 57 percent.
• At normal temperature and pressure, hydrogen chloride ($\mathrm{HCl}$) is a gas made up of the elements hydrogen and chlorine.
• Hydrochloric acid is the name for a gas solution in water.

Reason for $\mathrm{HI}$ has a higher boiling point than $\mathrm{HCl}$:

• From $\mathrm{HCl}$ to $\mathrm{HI}$, the boiling point rises. This trend, which correlates with the number of electrons in the molecules, is responsible for the growing intensity of the van der Waals intermolecular interactions.
• The diffuse electron cloud of the $\mathrm{HI}$ molecule allows for more successful intermolecular interactions (i.e. more attractive). So, $\mathrm{HI}$ should have a higher boiling point than $\mathrm{HCl}$.