I believe I have told you this before, but it is well worth repeating: this is an amazing website! Thank you for all the work you have done preparing it.

I am the guy scouring the internet trying to clen up the confusion about the pKa of water and the pKa of H3O+ and the pKb of OH-. I see that you have the correct value of 14 for the pKa of water, but I have noticed on this page in section 1 and in the table on https://www.masterorganicchemistry.com/2012/05/09/acid-base-reactions-ka-and-pka/#three
that you have the pKa of H3O+ as -1.74. It is actually 0.00 (Because the pKb (and pKa) of water is 14.00, then the pKa of water’s conjugate acid must be 0.00.) The pKb of OH- is also 0.00.

We just published an open access paper in Helvetica Chimica Acta (https://onlinelibrary.wiley.com/doi/10.1002/hlca.202400103) in which we show that the operation of a combination pH electrode is based on the fact that the pKa of H3O+ is 0.00. This paper also gives a thorough description of many other aspects of the pKa of water discussion. It is worth a read!

Thanks for listening!

It isn’t resonance. It’s an inductive effect, essentially.

Alkene carbons are sp2 hybridized and the electrons are held slightly closer to the nucleus. This has the effect of making sp2 hybridized carbons effectively more electronegative than sp3 hybridized carbons.

The effect is even stronger for alkynes (sp hybridized carbons) which have even higher effective electronegativity. For example the pka of propiolic acid is about 1.8.

In comparing H-I and H-F, when we lose a proton the charge will be directly on the atom (I- or F-). In that case it’s more stable on I(-) because as we go down a column of the periodic table the atoms get larger and can spread out their charge over a larger volume (polarizability).

In the case of the alcohol, the negative charge is actually on oxygen so polarizability is not a key difference here. The fluorine is electronegative and helps to reduce the amount of negative charge on oxygen through induction.