Ka1 vs Ka2 vs Ka3

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Nick_Ida 1D
Posts: 21
Joined: Sat Jul 09, 2016 3:00 am

Ka1 vs Ka2 vs Ka3

Postby Nick_Ida 1D » Mon Nov 28, 2016 10:26 am

Can someone please explain why as the Ka's increase in subscript, the attraction between opposite charges decrease? Is it because it is harder to separate the cation with the anion? I would love to know.

Julia Nakamura 2D
Posts: 33
Joined: Wed Sep 21, 2016 2:57 pm

Re: Ka1 vs Ka2 vs Ka3

Postby Julia Nakamura 2D » Mon Nov 28, 2016 11:32 am

So as Ka increases in subscript, it becomes more difficult to remove H+ ions from the acid because the ion is becoming more negatively charged (which makes it not want to remove any more H+ ions). For example, H2CO3 will give off one H+ to become HCO3-. However, it is harder for HCO3- to lose another H+ since it is already negatively charged.

Vincent Tse 2B
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Re: Ka1 vs Ka2 vs Ka3

Postby Vincent Tse 2B » Mon Nov 28, 2016 7:12 pm

Referring to page 158 in the course reader, a neutral species (which is in relations to Ka1) would have a higher acidity constant since it's more readily to give up an H+ as opposed to a negatively charged species (say Ka2) since anions would hold onto the H+ more strongly. Therefore, Ka2 would be smaller than Ka1 in regards to their acidity.

This concept is mainly seen in polyprotic acids and bases as they can give off more than one H+ (or accept, if base).

Hopefully this helped!

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