Just as in a solvent mixture it has a dielectric constant according to the molar fraction x of the components (measured or obtained by means of an average with a mixing rule), is it possible to do the same with polarity? That is, for example, if we know the polarity of the molecule of pure water and pure formamide, is it possible to know the polarity of a water-formamide mixture for different x's? Do you know recent literature on the subjec
Dear Sir,
please copy your question and insert it in Google Scholar and you ' ll find
a lot of hits about your question.
Among them , I send you the following article.
Article Quantitative Measures of Solvent Polarity
Please note that pure water can only obtained when you distill it twice under nitrogen. Formamide is very hygroscopic and must be distilled and dried . It is basic and must be stored , like water under nitrogen too.
Another hints in due course.
Good luck
Jean Rene Grezes alias JRG
Dear Amin,
for the mixtures of solvents probably the most suitable is an empirical Reichardt's polarity scale ET(30).
(Solvents and Solvent Effects in Organic Chemistry, Fourth Edition. Ed. by Christian Reichardt and Thomas Welton 2011).
Information about formamide-water mixtures you can find here:
Solute-solvent and solvent-solvent interactions in binary solvent mixtures. Part 8. The ET(30) polarity of binary mixtures of formamides with hydroxylic solvents (https://doi.org/10.1002/(SICI)1099-1395(199902)12:2%3C109::AID-POC97%3E3.0.CO;2-L).
Depends on whether the bulk polarity or the local polarity is wanted. Reichardt's polarity scale is a measure of local polarity, although it tends to include hydrogen bonding as well, so it's not just polarity. There are other solvatochromic probes that will also give a measure of local polarity. Bulk polarity is best measured by dielectric constant of the mixture using a capacitor.
Hi Amin,
if you need to know not the polarity, but dielectric constants of the water-formamide mixtures, just take the data from this publication:
Article Activity coefficients of NaF in aqueous mixtures with ??-inc...
or here:
Article Activity Coefficients of NaBr in Aqueous Mixtures with High ...
Hi Alexandre, thank you, it is very important article. I just asked on the possibility of the measure the polarity, because when I mixed tow solvant or more, i can't know their polarity
Hi Amin,
take into account that solvent polarity, based on dielectric constants gives you formamide more polar than water. All empirical scales, show that water is more polar. It will be only your decision which scale of polarity is more suitable for your measurements or calculations.
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