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Topic: Partition coefficient in extraction problems  (Read 1944 times)

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Offline mana

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Partition coefficient in extraction problems
« on: March 01, 2018, 03:54:35 PM »
hi all
I have solved 4gr butanoic acid in 100 ml water and I want to extract it with 100 ml benzene. the distribution constant (k) btw benzene and water is 3. I want to calculate the residual  butanoic acid remained in water after 3rd extraction with benzen.
I don't know in the formula for calculation residual extract, do I have to substitute 3 for k or 1/3 (because I'm calculating residual butanoic acid in water not in benzene)?
can anyone help :-\
and the formula is wn= w0(kv/kv+s/n)n
wn: the residual butanoic acid in water after n times extarction
w0: the amount of butanoic acid in water at first (4gr)
v: volume of water
s: volume of benzene

Offline Borek

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Re: Partition coefficient in extraction problems
« Reply #1 on: March 01, 2018, 06:10:04 PM »
Don't make things more complicated than they are, calculate how much was extracted and subtract from the initial.
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Offline mana

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Re: Partition coefficient in extraction problems
« Reply #2 on: March 01, 2018, 10:23:36 PM »
Don't make things more complicated than they are, calculate how much was extracted and subtract from the initial.
yes, you are right but I want to know how to calculate with formula too,  ???

Offline Borek

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Re: Partition coefficient in extraction problems
« Reply #3 on: March 02, 2018, 02:52:46 AM »
If you don't know how to follow the formula try to calculate the changes on the step by step basis - in each step you have known initial concentrations and initial volumes, that (and the fact total amount of the butanoic acid doesn't change) allows you to easily calculate final concentration ratio.
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