Need a solvent for a freezing point depression experiment. Acetic acid is the only one I know of, but it is not ideal due to the low freezing point depression constant. Any suggestions?
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$\begingroup$ does it have to be polar protic? Benzene is pretty good for FP depression experiments. $\endgroup$– Aniruddha DebSep 22, 2020 at 13:42
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$\begingroup$ @AniruddhaDeb I want a solvent like water, what do u think? $\endgroup$– Raze XIXSep 22, 2020 at 14:55
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$\begingroup$ What do you mean by telling acetic acid is not ideal due to the low freezing point depression constant? $K_f$ of acetic acid is larger than water. $\endgroup$– Mathew MahindaratneSep 22, 2020 at 18:45
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2 Answers
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Followings solvents have higher freezing point depression constants than that of water:
$$ \newcommand{\d}[2]{#1.&\hspace{-1em}#2} \begin{array}{lrr} \hline \text{Solvent} & \text{m.p.}/\pu{°C} & K_\mathrm{f}/\pu{°C m-1} \\ \hline \text{Water} & 0 & -1.86 \\ \text{Nitrobenzene} & 5.67 & -7.00 \\ \text{Cyclohexane} & 6.54 & -20.2 \\ \text{Acetic acid} & 16.6 & -3.90 \\ tert\text{-Butanol} & 25.82 & -20.2\\ \text{Phenol} & 43.0 & -7.27 \\ \hline \end{array} $$
So far, the best value is that of cyclohexene. Even though its melting point (m.p.) is $\gt \pu{25 ^\circ C},$ I also included phenol, just for curiosity.
answered Sep 22, 2020 at 19:29
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1$\begingroup$ @Buck Thorn: I voted to close under "Openion-based" when it is up. Then I found OP's comment of acetic acid, which is not correct. So I put the data I found as an answer for benefit of readers including OP. $\endgroup$ Sep 23, 2020 at 8:29
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Between $5$°C and $10$°C, you may find the following freezing points : 4-chlorotoluene, nitrobenzene, ethylenediamine, cyclohexane, decanol, formic acid.
Between $10$° and $15$°C, there is : acrylic acid, cyclooctane, dichloracetic acid, dioxane, oleic acid, paraldéhyde, phenylglycol, safrol, p-xylene, m-cresol, ethanolamine.
Between $15$°C and $20$°C, there is : acetophenone, dimethylsulfoxide, glyoxal, lactic acid, methacrylic acid, undecan-1-ol, butane-1,4-diol.
Between $20$° and $25$°C, there is : cyclohexanol, dodecan-1-ol, glycerol, hexadecane, heptadecane
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$\begingroup$ @AniruddhaDeb - so pick one that is? Lots of choices there. $\endgroup$ Sep 22, 2020 at 17:23