Question

Which of the following options best explains the trend in the boiling points of Group 7 hydrogen halides (HCl, HBr, HI) and its application?

Option 1: The boiling points increase from HCl to HBr to HI because of stronger hydrogen bonding in the larger, more polarizable iodine atom, making HI have the highest boiling point. This trend is important in the separation and purification of hydrogen halides in industrial processes.

Option 2: The boiling points decrease from HCl to HBr to HI due to increased molecular size and dispersion forces in the heavier halides. This trend is significant in the design of cooling systems in chemical reactors.

Option 3: The boiling points increase from HCl to HBr to HI due to decreasing molar mass, resulting in weaker intermolecular forces in HI. This trend is crucial in the formulation of pharmaceuticals containing hydrogen halides.

Option 4: The boiling points of HCl, HBr, and HI do not follow a clear trend, as the strength of intermolecular forces and boiling points depend on factors other than molecular size. This is relevant in understanding the behavior of hydrogen halides in various chemical reactions.

Answer 1

The boiling points increase from HCl to HBr to HI because of stronger dispersion forces in the larger, more polarizable iodine atom, making HI have the highest boiling point. This trend is important in the separation and purification of hydrogen halides in industrial processes.

Step-by-step explanation:

The trend in the boiling points of hydrogen halides (HCl, HBr, HI) can be explained by the increasing size and polarizability of the halogen atom. Option 1 is correct. As we move down Group 7, the size of the atoms increases, resulting in stronger dispersion forces between molecules.

This leads to higher boiling points. For example, HI has the highest boiling point because the iodine atom is the largest and most polarizable, allowing for stronger intermolecular forces.

This trend is important in the separation and purification of hydrogen halides in industrial processes. The higher boiling points of the hydrogen halides make it easier to separate them from other compounds during purification.