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I am carrying out a titration to determine the solubility of a carboxylic acid in mixtures of water and ethanol. I will be titrating a diluted (previously) saturated solution of water, ethanol and the acid against sodium hydroxide.

Can the sodium hydroxide interact with the ethanol so as to give an incorrect result?

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The hydroxyl group in ethanol has a pKa of about 16 (see wiki), which means you will not be able to deprotonate it using sodium hydroxide. Thus, the result of your titration should not be altered by the amount of alcohol in the solution.

Depending on the amount of ethanol I could envision that you are not determing solubility in pure water but in the sepcific mixture with ethanol, but that seems to be assumed in this kind of experiment, right ?

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  • $\begingroup$ Thanks for your answer - I came to the same conclusion, but forgot to add it as an answer. Nevertheless, it's nice to have confirmation! The experiment consists of determining the solubility of oxalic acid in mixtures of water and ethanol in different proportions. One follow-up question: I have used volume units to make up the solutions (i.e. 50mlH2O and 100mlC2H5OH) - is this appropriate? $\endgroup$ – Marcel Dec 7 '16 at 22:43
  • $\begingroup$ Sure why not. In case of water organic mixtures i usually use weight concentrations for calculations because volumes are not additive in this case and one has to be careful not to forget that. $\endgroup$ – simlan Dec 9 '16 at 10:41

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