% Ionisation or % 'Ionization' for non-Australians

[djsmith]

TL;DR

Is protonation in bases considered ionisation

Hi there,
I'm sure this is glaringly obvious for chem-buffs but just been coming across some Henderson-Hasselbach type questions in Basic scenarios where we're looking at basic solutions where calculating involves a [BH]/ as opposed to the regular [AH]/[A-].

I've come across wording in what I've read to make me think the [BH] form is considered ionised for bases hence the ratio eg 90:1 [BH]/ - 90%
I would assume in ordinary situations with [HA]/[A-] the % ionised would be the amount of A- (the ionic form) in solution and here 90:1 - 10%

Q: Is the resource I'm looking at wrong, is protonation in bases considered as ionisation or is my understanding of % ionisation wrong?

Thanks in advance,
David

 

[djsmith]

All good guys - I just found what I was after, it seems that a base is indeed considered ionised when protonated, I guess it makes sense being that its natural state is having a higher pKa. Thanks

 

[chemisttree]

Good on ya! I was still trying to figure out what y’all meant by “base”.

The only bazes that I know of that are ionized when protonated are amine bazes. Ammonium/Amine.

Other bazes like alkali and alkaline hydroxides, lithium alkyls, Grignards, alkali alkoxides, alkali amides, alkali silanoates are charged in their bazic form and neutral when protonated.

 

[djsmith]

Hmm must be that, the resource I was looking at was referring to amines but I wasn't sure if it was maybe a slip up or something. I'm going to chalk it up to be an exceptional circumstance and assume mostly we look at acid/base stuff with a HA/A lens rather than a BH/B.
Thanks, good to have someone shed some light, haven't come across any alkali silanoates but they sound interesting!

 

[chemisttree]

Alkali silanoates.

 

[djsmith]

Thanks

 

[Terrakron]

Summary:: Is protonation in bases considered ionisation

Hi there,
I'm sure this is glaringly obvious for chem-buffs but just been coming across some Henderson-Hasselbach type questions in Basic scenarios where we're looking at basic solutions where calculating involves a [BH]/ as opposed to the regular [AH]/[A-].

I've come across wording in what I've read to make me think the [BH] form is considered ionised for bases hence the ratio eg 90:1 [BH]/ - 90%
I would assume in ordinary situations with [HA]/[A-] the % ionised would be the amount of A- (the ionic form) in solution and here 90:1 - 10%

Q: Is the resource I'm looking at wrong, is protonation in bases considered as ionisation or is my understanding of % ionisation wrong?

Thanks in advance,
David

I would say that the language indicates a direction for the reaction so the self-ionization of water would be 2H2O —> H3O+ (hydronium) + OH- (hydroxide) not the other way around.