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Topic: Which buffer solution will have the the lowest pH?  (Read 5822 times)

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Offline slayer

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Which buffer solution will have the the lowest pH?
« on: December 12, 2006, 11:49:47 PM »
NH3 / NH4Cl

PO43- / HPO42-

HSO3- / KOH

I initially assumed that HSO3- / KOH was the lowest pH because sulfuric acid is a very strong acid and KOH is a strong base, so they would both dissociate entirely.

is this a correct assumption?

Offline Borek

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Re: Which buffer solution will have the the lowest pH?
« Reply #1 on: December 13, 2006, 05:18:53 AM »
Assumption is wrong, this is sulfurous acid, not sulfuric. And in a way you have posted the same question twice, shame on you. Finallly, you still haven't decided whether it is a buffer solution, or not.
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Offline slayer

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Re: Which buffer solution will have the the lowest pH?
« Reply #2 on: December 13, 2006, 01:36:59 PM »
And in a way you have posted the same question twice, shame on you.

yea sorry about that borek. It was actually a two part problem where the first part I had to identify the above three as being buffers among a set of 6 combinations. I missed the HSO3- / KOH, so now I have to explain why it is a buffer system.

The second part of the problem was which of the buffer systems you selected has the lowest pH.  But if I was to establish which of the conjugates appeared to be more acidic, that would be the lowest pH, right?

Offline AWK

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Re: Which buffer solution will have the the lowest pH?
« Reply #3 on: December 14, 2006, 02:51:12 AM »
Quote
HSO3- / KOH
This solution cannot exist.
KOH will react with HSO3- anion to form SO32- anion, and both anions eventually form a buffer solution
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