[vizakenjack]

So uhm... why aren't there any?

[billnotgatez]

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[vizakenjack]

We are a teaching forum here and forum rules require you show some work.

This isn't a problem that requires calculation... or steps... it's a concept question... I guess.
So I dunno what you're nagging about... 

HCl give off a cation H⁺ and an anion Cl^-. So cations CAN come from acids...

[kriggy]

Think about lewis acid base theory:
http://en.wikipedia.org/wiki/Lewis_acids_and_bases

What are features of acids and bases?

[vizakenjack]

What are features of acids and bases?

Why can't you just answer the question -.- ...


Acid donates a proton (H)
Base accepts it...
and?

[Borek]

What are features of acids and bases?

Why can't you just answer the question -.- ...

You were asked to THINK about why, have you tried?

Acid donates a proton (H)
Base accepts it...
and?

Good, now try to write a reaction that the Basic cation would undergo. Does it look reasonable, or not? Why yes, why not?

[vizakenjack]

Good, now try to write a reaction that the Basic cation would undergo. Does it look reasonable, or not? Why yes, why not?

What kind of a reaction?
Like, the amphiprotic (donates/accepts H⁺) sulfuric acid?
HSO₄ + H₂O -> H₃O⁺ + SO₄⁺
or
HSO₄ + H₂O -> OH^- + H₂SO₄

Detailed ionic would look like this? (I thought you can only write them for salts... but whatever):
H⁺ + SO₄^- + H₂O ...
?
Cation H⁺ reacts in both cases, so...?

[Borek]

Good, now try to write a reaction that the Basic cation would undergo. Does it look reasonable, or not? Why yes, why not?

What kind of a reaction?

Reaction that is responsible for the fact ions/substances listed in the table are classified as basic or acidic. That's what the question is about.

[Irlanur]

what would a reactions look like if a cation catches a proton?

[clarkstill]

I think the question is wrong. Why can you have acidic anions and not basic cations? What about this diamine (attached)?



Surely at a sufficiently low pH the second amine will protonate? Surely this is the precise analogue of the HSO4- etc. used as examples of "acidic anions"?

[Borek]

Why can you have acidic anions and not basic cations?

That's what the question is about.

You are not completely off with your thinking, but you are ignoring an important difference which makes things interesting. Think about size.

[clarkstill]

Why can you have acidic anions and not basic cations?

That's what the question is about.

You are not completely off with your thinking, but you are ignoring an important difference which makes things interesting. Think about size.

Size matters not. Are you really saying that at pH -50 the molecule I drew wouldn't be protonated on both nitrogens? The fact it might cleave a la acetal might make it practically a bad idea, but in theory there is nothing preventing it.

[Borek]

Size matters not. Are you really saying that at pH -50 the molecule I drew wouldn't be protonated on both nitrogens? The fact it might cleave a la acetal might make it practically a bad idea, but in theory there is nothing preventing it.

Straw man. I never said diamine can't be doubly protonated.

Besides, while the negative pH is possible, pH of -50 is definitely not. Throwing random numbers around is not a best way of arguing your point.

As I said many posts earlier, we should start with a reaction equation.

[Dan]

I don't see why clarkstill's example is not an example of a basic cation.

If a base can be doubly protonated, surely there is a basic cation. What about hydrazine - both the mono- and dihydrochlorides are commercially available?

[Borek]

Ah, hidden assumptions.

From the content of the table posted in the original question I think it refers not to large, organic cations, but to small, inorganic ones.