why HF is weaker acid than HCL
Answers
Answered by
7
There are at least two reasons.
1. Fluorine has high affinity for hydrogen, and the H-F bond is quite difficult to break.
2. Because of high electronegativity of F, there is strong, extensive hydrogen bonding among the HF molecules which makes it quite difficult for release of H as H+ ion in water.
1. Fluorine has high affinity for hydrogen, and the H-F bond is quite difficult to break.
2. Because of high electronegativity of F, there is strong, extensive hydrogen bonding among the HF molecules which makes it quite difficult for release of H as H+ ion in water.
laba46:
Exactly right brother.
thanks
Answered by
0
The effects of both entropy and enthalpy reduce the acidity of HF compared to HCl and HBR.
Explanation::
Acid strength, i.e. the degree that the forward reaction goes to completion, depends on (i) the strength of the HX bond, and (ii) the degree that the halide is solvated.
For HF, there is better overlap in H−Xbecause the fluoride ligand is smaller than the lower halides; this is an enthalpy effect. Moreover, the fluoride ligand, F−, is smaller and more polarizing, and more effectively solvated by solvent molecules. Since fluoride is smaller and more polarizing, it causes more solvent order and the forward reaction is disfavoured.
Since both entropy and enthalpy is disfavoured with respect to fluoride, the result is that HF is a poor acid compared to HCl, HBr, etc. The entropy effect is probably most significant.
Note that fluoride salts give basic solutions in water:
NaF(aq)+H2O(l)⇌HF(aq)+−OH+Na+
Explanation::
Acid strength, i.e. the degree that the forward reaction goes to completion, depends on (i) the strength of the HX bond, and (ii) the degree that the halide is solvated.
For HF, there is better overlap in H−Xbecause the fluoride ligand is smaller than the lower halides; this is an enthalpy effect. Moreover, the fluoride ligand, F−, is smaller and more polarizing, and more effectively solvated by solvent molecules. Since fluoride is smaller and more polarizing, it causes more solvent order and the forward reaction is disfavoured.
Since both entropy and enthalpy is disfavoured with respect to fluoride, the result is that HF is a poor acid compared to HCl, HBr, etc. The entropy effect is probably most significant.
Note that fluoride salts give basic solutions in water:
NaF(aq)+H2O(l)⇌HF(aq)+−OH+Na+
Similar questions