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Topic: Why strong acid has weak conjugate base?  (Read 10524 times)

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Offline Astrokel

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Why strong acid has weak conjugate base?
« on: April 23, 2008, 10:03:27 AM »
I understand that strong/weak acid has weak/strong conjugate base.

I'm just wondering why is that so?

My teacher explained to me through following argument.

If HCOOH is a strong acid, then HCOOH ---> HCOO- + H+

HCOOH will dissociate completely.

and if HCOO- is a strong base, then it will react with the H+ ions to form back HCOOH.

This apparently contradict each other, thus strong acid must have a weak conjugate base or vice versa.

I've no problem in following the arguments, and is just wondering any molecular explanations?

Thanks,

Kelvin  ;D






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Offline p3t3r1

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Re: Why strong acid has weak conjugate base?
« Reply #1 on: April 23, 2008, 05:22:54 PM »
If it is a strong acid, it wants to lose proton really really bad. Therefore, its conjugate base won't be able to grab on proton well and therefore will be weak. (If its conjugate base can grab on to the proton well then there wouldn't be a 100% dissociation in the first place. It would like to stay in its acidic HA form)

Offline Astrokel

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Re: Why strong acid has weak conjugate base?
« Reply #2 on: April 24, 2008, 08:55:51 AM »
thanks!  ;)
No matters what results are waiting for us, it's nothing but the DESTINY!!!!!!!!!!!!

Offline AWK

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Re: Why strong acid has weak conjugate base?
« Reply #3 on: April 24, 2008, 09:01:22 AM »
Ka x Kb = Kw
AWK

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