LuckyWinner
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Crystallizing out 2 Compounds from Each other - How much Solvent to use?
The question, I want to separate these 2 compounds from each other
by using their high difference in water solubility.
You have :
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Compound A : 10grams
Compound B : 70 grams
Solubility:
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Compound A
Solubility in water:
10 g/100 cc @ 20 °C;
30 g/100 cc @ 100 °C;
Compound B
Solubility in water:
200 g/100 cc @ 20 °C;
300 g/100 cc @ 100 °C;
the calculation
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is 'solubility in water grams' is divided by compound grams you have ,
100cc of water is then divided by this number to get the min amount of water needed to dissolve your compound.
@ 100C water,
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when these 2 compounds are dissolved in 100ml of water at 100C.
Compound A : 10grams can be dissolved in 33ml of water.
Compound B : 70 grams can be dissolved in 23ml of water.
I need a min of 33+23ml of water = 56ml of water to dissolve both of these compounds in 100C water.
@ 25C water
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Compound A : 10grams can be dissolved in 100ml of water.
Compound B : 70 grams can be dissolved in 35ml of water.
I need a min of 100+35ml of water = 135ml of water to dissolve both of these compounds in 25C water.
Question:
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Now the question is, the correct amount of water to use to separate compund A from B.
Both can be dissolved in 56ml of 100C water.
if these 56ml of water are cooled down to 25C from 100C.
there are 135ml- 56ml = 79ml of water missing to dissolve both compounds.
how does compound B and A use this 56ml, what is the % of each compound
in these 56ml?
56ml of water could dissolve at 25C
Compound A =5.6 grams (4.6g will already be crashed out)
Compound B= 112 grams (70g fully dissolved)
but when I have
Compound A : 10grams
Compound B : 70 grams
how do these 2 share this amount of water?
Goal is the highest yield/purity of Compound B 70 grams.
[Edited on 21-11-2020 by LuckyWinner]
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Maurice VD 37
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What would be known is how much A is soluble in a saturated solution of B, and how much B is soluble in saturated solution of A. And this is unknown.
Or you have admitted that these two unknown but required values are equal to zero.
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yobbo II
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Look up a graph of mutual solubility of the two compounds and if you obtain one you can study the attached. It's quite a pain. You cannot simply
seperate them unless one is very soluble and the other is insoluble.
Yob
Attachment: Desktop.rar (494kB)
This file has been downloaded 199 times
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