Question

why is HCl a gas at room temperature and HF a liqid .

Answer 1

HF forms stable H bond . but HCl doesn't forms

Answer 2

⭕️In HF, fluorine has highest electronegative character.

⭕️It has the capacity to establish Hydrogen bon with other HF molecule.

⭕️HF has a very strong permanent dipole, so it forms stronger permanent dipole-permanent dipole forces with other HF molecules.

⭕️The strength of these permanent dipoles is caused by the electronegativity of fluorine➖which is the heighest !

⭕️Therefore, HF molecules are very polar .

⭕️This property is not observed in HCl therefore HF exist in liquid state while HCl exist in gaseous state.

⭕️Hydrogen chloride does not contain hydrogen bonding. even though we know that chlorine has the same electronegativity as nitrogen, oxygen and fluorine.

⭕️The reason is that a cl atom is much bigger than atoms of oxygen, fluorine, or nitrogen.

⭕️So they are not having strong attraction between a chlorine atom.

⭕️So we can say that HCl a gas at room temperature.


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