Question

$H_{2}O$ has a higher boiling point than $HF$ because:

• A. $H_{2}O$ is more polar than $HF$
• B. $H_{2}O$ can form more hydrogen bonds
• C. $H_{2}O$ has a higher molecular weight
• D. $H_{2}O$ has more atoms
• E. $H_{2}O$ does not have a higher boiling point that $HF$

Answer 1

The correct option is B $H_{2}O$ can form more hydrogen bonds

Option $B$ is the correct answer.

Both $H_{2}O$ and $HF$ have electronegative oxygen and fluorine atoms respectively in their molecule. In fact, Fluorine is more electronegative than Oxygen, so technically, $HF$ should engage in more hydrogen bonding than water. But the scenario is different.

Each water molecule has two hydrogen atoms. Whereas, each $HF$ molecule has only one hydrogen atom. And hence, water molecule takes part in extensive and more hydrogen bonding than Hydrofluoric acid. Water molecule through its extensive hydrogen bonding forms a bulky molecule and it is very difficult to break its bonds. A large amount of energy is required to break all its bonds. Thus $H_{2}O$ has a higher boiling point than $HF$.