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Author: Subject: Video: Determine the Enthalpy change in hydration, problem occurs.
coccoc
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smile.gif posted on 28-10-2009 at 06:03
Video: Determine the Enthalpy change in hydration, problem occurs.


I did this experiment few days ago, and I found the error is quite large, besides the error from my apparatus, what is the main error that cause error in the result.
I noticed that anhydrous MgSO4 form milky solution when dissolved in water, is that the cause?

http://www.youtube.com/watch?v=mCMPrnKzJIs

http://www.youtube.com/user/Cforchemistry




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jokull
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[*] posted on 28-10-2009 at 15:29


How much solid did you use?

The difference may arise from the concept of Hydration Enthalpy. Let me give some definitions:

Enthalpy of hydration (Hhyd), of an ion is the amount of energy released when a mole of the ion dissolves in a large amount of water forming an infinite dilute solution in the process.

This hydration energy consists of two inseparable parts. The first part is the energy released when the solvent forms a coordination compound with the ions (this is called energy of ligation, Hlig).
The second part is to disperse the ions (or hydrated ions) into the solvent medium, this amount of energy is called energy of dispersion, Hdisp.

Maybe you are disregarding the energy of dispersion in your calculations.


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coccoc
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[*] posted on 29-10-2009 at 07:12


I did revise the calculation and it is ok,
maybe I have to use more water to dissolve it.




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