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Thread: Determination of solubility

  1. #1 Determination of solubility 
    Forum Junior ArezList's Avatar
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    Hi all and again..

    Does anyone know what's the determination of the solubility of a certain substaince.

    Someone says that it'll dissolve less in an acid solution than pure waater if the solute is acidic. And for basic solute vice versa.Is this fair enough?

    Take CO2 for examle, as with pure water and HCl solution at room temperature which will absorb more gases?


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  3. #2  
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    Fair enough.

    An acidic solute will dissolve more readily if the water is basic, and a basic solute will dissolve to a greater extent in acidic solution.

    CO2 gas is neutral but it reacts with water to form carbonic cid, H2CO3. Therefore CO2 dissolves more readily in alkali solution. In fact, NaOH solutions used as standards must be prepared fresh daily because in 24 hours they absorb too much CO2 from the air.


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  4. #3  
    Forum Junior ArezList's Avatar
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    But "the soluable" here are not the same.

    CO2 is in fact react with the NaOH solution. and formed a lot of Na2CO3 and some amount of NaHCO3. when you heat the solution. There won't be the same amount of gas come out as Na2CO3 is hardly dissolved.

    I should restrict the defination of soluablility here. A gas dissolve in a lovent to form a solution from which you can get the same amount of gas as started only by some physical methods.

    Then, I woder what's the key that decides the "solubility" of a certain gas?
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  5. #4  
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    You can indeed recover CO2 that has dissolved in NaOH solution. Just acidify the solution. This is a standard laboratory technique.

    You seem to be trying to invent your own definition of solubility. Note that the solubility data in the various reference tables make absolutely no distinction between solutes that do not react with water (He, O2, N2) and those that do (CO2, NH3, SO2, SO3). Stuff that enters solution is soluble, period.
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  6. #5  
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    Note that the solubility data in the various reference tables make absolutely no distinction between solutes that do not react with water (He, O2, N2) and those that do (CO2, NH3, SO2, SO3).
    Yeah you are rigth the definition of "soluable " here is the one created by myself:

    I should restrict the defination of soluablility here. A gas dissolve in a lovent to form a solution from which you can get the same amount of gas as started only by some physical methods.
    Such as heating or cooling,,etc,
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  7. #6  
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    Well. I in turn don't think as with CO2, the PH of the solute will make too much difference. Because only very little CO2 will react with water to form H2CO3....
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