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I wanted to make some ethanol from baker's yeast and I used sucrose. I've made it and put it in a glass jar. I left it on a warm place (near the radiator) until the yeast died and after they died I distilled the yellowish liquid using simple distillation. When I smelled the product in the receiving flask I was confused. It resembled ethanol a little. The smell was like sweet and medium-intense ethanol. I think that it might be methanol. If there are any reagents or tests other than smelling that I can use at home, please do tell.

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  • $\begingroup$ Do you want to know whether there are impurities at all, what the impurities are, or the concentrations of the impurities? If you were careful about measuring your inputs, you may be able calculate expected refractive index and density and compare those to the actual for under $30 of equipment. $\endgroup$ – ericksonla Apr 3 '18 at 17:55
  • $\begingroup$ I just wanted a simple test for presence of methanol (don't need to measure the quantity). $\endgroup$ – Adinex Apr 3 '18 at 18:06
  • $\begingroup$ Do you have iodine solution and sodium hydroxide? rsc.org/learn-chemistry/resource/res00000548/… $\endgroup$ – JavaScriptCoder Apr 3 '18 at 18:09
  • $\begingroup$ Yes, the NaOH is at hand and I can buy the iodine at the pharmacy. Thanks! $\endgroup$ – Adinex Apr 3 '18 at 18:11
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Sorry @ JavaScriptCoder, but I've to agree with aventurin. I'd say idoform test should have been done in a certified laboratory because of safety concern. However, I think fractional distillation might be helpful for this identification (or simply verification). Adinex can do this at home since he/she has done simple distillation at home. Ethanol/water binary system give an azeotrope, which boils at 78.1 °C and gives 95 % ethanol. Methanol, on the other hand, make no azeotrope with water, and boils at 64.7 °C. The temperature range of 13.4 °C need only about ≤20 theoretical plates to separate. If you get first distillate below, say, 67 °C, then you got methanol or something other than ethanol. So, don't drink it.

For more information, read the Wikipedia page having Azeotrope tables.

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There's probably no reliable chemical test for the presence of methanol in alcohol mixtures that could be carried out at home without decent laboratory equipment.

Qualitative tests such as esterification with boric acid and subsequent flame test or oxidation to formaldehyde and its detection are unreliable, especially in the presence of ethanol. I advise against using such tests to decide about the presence of methanol in distilled liquors.

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I have decided to format my comment into an answer.


To distinguish the ethanol from methanol, have three test tubes. In one of them, put $\pu{2 mL}$ known methanol, in one of them $\pu{2 mL}$ known ethanol, and one of them $\pu{2 mL}$ your mystery solution. Then, apply about $\pu{5 mL}$ of $\pu{0.5 M}$ of $\ce{I2}$, and about $\pu{10 mL}$ $\pu{1 M}$ $\ce{NaOH}$ to each test tube in that order. If your chemical is ethanol, the reaction will produce $\ce{CHI3}$, which is harmful (make sure to dispose of it properly). However your alcohol won't kill you unless you drink to excess. Otherwise, your chemical is methanol, which is poisonous (make sure to dispose of that properly also). Definitely don't drink that.


Source is from the Royal Society of Chemistry. It also linked this source.

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    $\begingroup$ This does not answer the question since the test can not show the presence of methanol in the distilled liquid. $\endgroup$ – aventurin Apr 3 '18 at 18:56
  • $\begingroup$ @aventurin he simply asked how to distinguish methanol or ethanol. I provided a distinguishing test. $\endgroup$ – JavaScriptCoder Apr 3 '18 at 18:57
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    $\begingroup$ The question is "how to test for methanol?" $\endgroup$ – aventurin Apr 3 '18 at 19:02

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