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blazingwes

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help on buffer question
« on: April 14, 2006, 12:23:26 PM »
i need help on one of my questions on my hw assignment.. i don't know how to do it.

how you one make a one liter solution with a pH os 5.00, so that it will be buffered?  (Use a 0.100 M acid solution)

wath is the pH of the solution if acid is added so that the Hydrogen ion concentration is .100M

Offline Borek

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Re: help on buffer question
« Reply #1 on: April 14, 2006, 01:37:17 PM »
What acid? Do you know what Henderson-Hasselbalch equation is?
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blazingwes

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Re: help on buffer question
« Reply #2 on: April 14, 2006, 01:55:44 PM »
soo will this be the correct answer?
adding .100 M of nitrous acid to 4.47 M of nitrite to get a buffer of ph 5.00..

but.. i don't understand the 2nd question

Offline Borek

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Re: help on buffer question
« Reply #3 on: April 14, 2006, 02:11:06 PM »
For pH 5.0 acetic acid will be much beter. Nitrous acid has pKa = 3.37, with pH 5.0 you are too far from the pKa for buffer to be effective, see plot at buffer capacity lecture.

Looks like the second question has nothing to do with buffers :)
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blazingwes

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Re: help on buffer question
« Reply #4 on: April 14, 2006, 02:54:25 PM »
one more question wat is a singel-step equation????


how you write BaSO3 +H+ = Ba2+ + H2SO4

Offline Alberto_Kravina

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Re: help on buffer question
« Reply #5 on: April 14, 2006, 02:57:37 PM »
Quote
how you write BaSO3 +H+ = Ba2+ + H2SO4

Err....I think that something is wrong! It should be BaSO4 + H+ ----> Ba2+ + H2SO4

Well, try to solve it by yourself, it's pretty easy....

Offline AWK

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Re: help on buffer question
« Reply #6 on: April 15, 2006, 06:39:28 AM »

Err....I think that something is wrong! It should be BaSO4 + H+ ----> Ba2+ + H2SO4

Well, try to solve it by yourself, it's pretty easy....
Quote
But wit nitric acid this reaction is possble!
BaSO3 + H(+) + NO3(-) = Ba2+ + SO4(2-) +NO +H2O (unbalanced !)
AWK

Offline Alberto_Kravina

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Re: help on buffer question
« Reply #7 on: April 15, 2006, 07:15:27 AM »
I know that the sulfite anion can be oxidated to Sulfate, however, I thought that the reaction that blazingwes meant was just the protonation of the sulfite anion with a (strong) acid.... :(

Offline Borek

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Re: help on buffer question
« Reply #8 on: April 15, 2006, 08:35:48 AM »
I am afraid even blazingwes is not 100% sure what s/he is asking about :(
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