Q. 22

[dnpgr16513]

Does this have to do anything with HF being a weak acid? Being a weak acid wouldn't F- be a strong conjugate base? Am I totally off here?

thanks.

[jellywing_2058]

I see what you are saying. F- would be a strong conjugate base if it was derived from a weak acid like HF for example. It is not the case here.


As mentioned in the explanation, a base accepts a proton. In all three molecules, the proton will go to the N, which has a lone pair (F and Cl do have 3 lone pairs each, but halogens do not make 2 bonds; missing only one electron to fill the p orbital. Fill the atomic orbitals box diagram for clarification)

In order to solve this problem, you need to look at the electronegativity of the Cl and F.

Knowing that a Halogen is very electronegative, it will "pull" the electrons of the N toward itself, which makes the N have a less negative characteristic.

Since F is more electronegative than Cl, F will pull more electrons, making the N more delta positive.

The N being the more delta positive will have a harder time attracting a proton.

Hope this helps!

[dnpgr16513]

definitely helpful. thanks so much