Strengths of Acids: Polarity

[Ayesha Aslam-Mir 3C]

When looking at a list of strong acids, I see polar covalent compounds, but I don't quite understand if strong acids or more or less polarizable than weak acids?

[Steph Du 1H]

I don't think that we need to look at polarity for determining the strength of an acid. The strength of an acid can be determined based on bond length (longer bonds = weaker bonds = easier to remove H+ = stronger acid) and the stability of the resulting anion (resonance and electron withdrawing atoms make it more stable = stronger acid).

[Shreya Patel- 2D]

It's probably safe to assume that stronger acids have weaker and more polar hydrogen-X atom bonds because strong acids are more likely to give off their protons.

[Ayesha Aslam-Mir 3C]

It's probably safe to assume that stronger acids have weaker and more polar hydrogen-X atom bonds because strong acids are more likely to give off their protons.

Wouldn't higher polarity make it a theoretically stronger-weak acid? For example, HI has a more polar bond that HBr but since HBr is bigger is dissociates easier?

[Ximeng Guo 2K]

I think since the halogens are in the same group and all have 7 valence e-, the effect of electronegativity leading to polarization is not significant as the effect of bond length.
Thus, the strength of H-X bond is mainly due to bond length.
Longer bond = weaker bond = much easier to dissociate H+ = stronger acid.

[805593945]

I don't think being more polarizable has to deal with acidity. From the lecture, I remember that there are two scale to determine relative acidity: 1.How easy a molecule loses its proton and 2. anion stability after losing the proton.
Longer bond length, thus easier to remove proton makes a molecule more acidic.
A more stable anion, either through resonance or the withdrawing toms, will be make the acid more acidic.

[Keshav Patel 14B 2B]

When looking at the strength of acids always look at its ability to give off a hydrogen. When its a bigger a element it has longer bonds so it has a smaller bond on the hydrogens. But I see your point and yes stronger acids typically have a higher polarizability because it has more electrons and a larger electron cloud and that is why the bonds are longer.