Melting and Boiling point out of Hydrogen Fluoride (HF) are higher than Hydrochloric acid (HCl), Hydrobromic mountain (HBr) and Hydrogen iodide (HI).

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Fluorine has the highest possible electronegativity of an atom. When fluorine bonds v hydrogen, the polarity is so strong that it begins to exhibit the residential property of hydrogen bonding, i m sorry is in concentrate just an excessive dipole. Chlorine just doesn’t have actually the pull of its halogen counterpart and also can’t form that polar of a molecule.

According come Fajan’s rule with the rise of the size of anions, the tendency to be polarized increases. Because, as the size of anion increases, the distance between its nucleus and also outermost electrons increases and also hence the cell nucleus can tempt the electron less. Therefore the cation can more easily deform the anion. Because of this in any kind of group in the periodic table the tendency of the anion to be polarized boosts from optimal to bottom. Because that example, the radii that the halide ions are as follows.

F– (1.33A) – (1.81A) HCl > HBr > HI

Again, because of the existence of hydrogen bond in Hydrogen Fluoride (HF) molecule, it’s melting and also boiling points room higher. Fluorine has actually a higher electronegativity 보다 the various other halogens which way for fluorine it experience hydrogen bonding which offers it a boiling allude of about 19 degrees Celcius. Conversely, hydrogen chloride boils at -80.05 degrees Celcius. The various other halogens being much less electronegative than Fluorine would therefore not type hydrogen bonds come a degree that fluorine does.


Hence the intermolecular force in between the molecules of HF compound boosts which causes greater melting and boiling points. But in the situation of HCl, HBr, and HI, they can’t form a hydrogen bond. Hence their melting and also boiling points are lower than HF.

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Due to the high electronegativity the fluorine hydrogen bonds have the right to be formed between HF molecules. Hydrogen bond require more energy come break that London Forces. The various other halogens are not together electronegative and also so various other hydrogen halides cannot form hydrogen bonds between molecules. Therefore an ext energy is compelled to rest the intermolecular forces in HF than the various other hydrogen halides and so it has actually a higher boiling point. More powerful hydrogen bonding leader to a higher boiling point. Thus you have actually a higher charge difference between the hydrogen atom and the fluoride atom causing a greater attraction and strongness the the hydrogen bonding.