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I have a result from an experiment that really bothers me, yet I found no sources online that can explain the situation.

While quinine is relatively soluble in ethanol because they are both non-polar. However, the result was not homogeneous. Even worse, the solution freezes when we left it sitting for a moment (it turns into solid mass), certainly not within our expectations. what we did was preparing 300 mg of quinine and dissolve it into 10 ml of ethanol and spin it in vortex spinner for 2 minutes.

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The solubility of quinine sulfate in ethanol is temperature dependent. This reference 1 describes it as slightly soluble in EtOH at 25C, soluble at 80C. What you describe sounds like the material crystallised out of solution when you let it stand.

Note: Ethanol is generally regarded as a polar solvent, and while the freebase of quinine is non-polar, any salt of it is highly polar.

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  • $\begingroup$ so i have gotten the wrong idea about the polarity. though i still believe that we can dissolve non polar molecule in ethanol? but why did our solution crystallised when we let it stand? is there any relation towards the freezing point then? more importantly, what is the evaluation towards the solubility since it has crystallised? are we going to say that quinine is insoluble in EtOH? could you please explain further on this? $\endgroup$ – kurniadi gautama Nov 21 '18 at 12:40
  • $\begingroup$ My speculation is that spinning it also heated it, when you let it stand it cooled and the material that had dissolved crystallised out. Quinine freebase is EtOH soluble (1g/0.8ml). Do you need the solution to be of the salt? $\endgroup$ – Waylander Nov 21 '18 at 12:46
  • $\begingroup$ if you can provide, please do so, i need as many informations available apparently $\endgroup$ – kurniadi gautama Nov 21 '18 at 13:30
  • $\begingroup$ Solubilty taken was taken from here: mpbio.com/product.php?pid=02150152&country=222 $\endgroup$ – Waylander Nov 21 '18 at 13:59
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    $\begingroup$ Thanks to @mathew-mahindaratne This may be relevent en.wikipedia.org/wiki/Organogels $\endgroup$ – Waylander Nov 22 '18 at 11:11

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