Suggest a reason why HF is a weak acid, whereas binary acids of the al

1.	Suggest a reason why HF is a weak acid, whereas binary acids of the all other halogens are strong acids.
Answer» The hydrogen halides are extremely soluble in water due to the ionisation. X + H₂O → H₃O⁺ + X^- (X = F, Cl, Br or I) Solutions of hydrogen halides are therefore acidic and known as hydrohalic acids. Hydrochloric, hydrobromic and hydroiodic acids are almost completely ionised and are therefore strong acids but HF is a weak acid. For HF, HF + H₂O ⇌ H₃O⁺ + F^- HF + F^- → HF₂^- At high concentration, the equilibrium involves the removal of fluoride ions is important. Since it affects the dissociation of hydrogen fluoride, therefore it is a weak acid.

Suggest a reason why HF is a weak acid, whereas binary acids of the all other halogens are strong acids.

Answer»

The hydrogen halides are extremely soluble in water due to the ionisation.

X + H₂O → H₃O⁺ + X^-

(X = F, Cl, Br or I)

Solutions of hydrogen halides are therefore acidic and known as hydrohalic acids. Hydrochloric, hydrobromic and hydroiodic acids are almost completely ionised and are therefore strong acids but HF is a weak acid. For HF,

HF + H₂O ⇌ H₃O⁺ + F^-
HF + F^- → HF₂^-

At high concentration, the equilibrium involves the removal of fluoride ions is important. Since it affects the dissociation of hydrogen fluoride, therefore it is a weak acid.

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