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Author: Subject: Solubility with multiple compounds - how do they effect each other?
RogueRose
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[*] posted on 4-12-2016 at 17:53
Solubility with multiple compounds - how do they effect each other?


I'm curious how adding multiple compounds such as NaCl and KNO3 into water would effect the amount of each compound that can be dissolved at any given temp. Lets say that NaCl can dissolve at 300g/L and KNO3 at 800g/L at the same temp (20-25C) - when each is dissolved individually. If both are dissolved into the same liter of water, will it dissolve 300g & 800g of the salt and nitrate respectively or will it be greatly reduced like 150g and 400g or 200g & 600g?

I'm interested in other compounds like CuSO4, Ca(NO3) and KCl (really take your pick of salts....) mixed together and finding out how they effect total solubility of each compound when compared to other compounds in the mix. So more than 2 compounds I'm also wondering about.

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HeYBrO
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[*] posted on 4-12-2016 at 18:42


here read these:
http://chem.libretexts.org/Core/Physical_and_Theoretical_Che...
http://chem.libretexts.org/Core/Physical_and_Theoretical_Che...
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Metacelsus
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[*] posted on 5-12-2016 at 05:43


You should read up on activity coefficients and ionic strength. In many cases, a high concentration of one salt will allow more, not less, of an unrelated salt to dissolve.



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RogueRose
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[*] posted on 5-12-2016 at 06:17


Quote: Originally posted by Metacelsus  
You should read up on activity coefficients and ionic strength. In many cases, a high concentration of one salt will allow more, not less, of an unrelated salt to dissolve.


Wow! That is totally unexpected! I'll look into this. That make some things very interesting!!
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yobbo II
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[*] posted on 5-12-2016 at 07:49


Quote: Originally posted by Metacelsus  
You should read up on activity coefficients and ionic strength. In many cases, a high concentration of one salt will allow more, not less, of an unrelated salt to dissolve.


Surly that cannot be right?

Start here for just two compounds.

https://www.sciencemadness.org/whisper/files.php?pid=252390&...
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solo
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[*] posted on 5-12-2016 at 08:06


...maybe a pictorial might help.....solo

https://www.khanacademy.org/science/chemistry/acid-base-equi...




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Metacelsus
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[*] posted on 5-12-2016 at 08:57


Quote: Originally posted by yobbo II  
Quote: Originally posted by Metacelsus  
You should read up on activity coefficients and ionic strength. In many cases, a high concentration of one salt will allow more, not less, of an unrelated salt to dissolve.


Surely that cannot be right?


Quote:

In general, the addition of an “inert” salt (KNO3) to a sparingly soluble salt (CaSO4) increases the solubility of the sparingly soluble salt.

http://chem320.cs.uwindsor.ca/Notes_files/320_l07.pdf

Yes, this is counterintuitive. Conceptually, the potassium and nitrate ions "shield" the calcium and sulfate ions from each other.

[Edited on 12-5-2016 by Metacelsus]




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DraconicAcid
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[*] posted on 5-12-2016 at 09:06


Quote: Originally posted by yobbo II  
Quote: Originally posted by Metacelsus  
You should read up on activity coefficients and ionic strength. In many cases, a high concentration of one salt will allow more, not less, of an unrelated salt to dissolve.


Surly that cannot be right?


Sure it is. If you have a high ionic strength, the solution ceases to be pure water (or "just like pure water"), and becomes more similar to an ionic liquid. Ergo, ionic compounds become more soluble in it. There are some hydrated ionic salts that can be used as low-temperature melts (calcium nitrate tetrahydrate, I recall, is one of them); you could view it as a molten salt containing some water, or a really really concentrated calcium nitrate solution.




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