Noob I am
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Methanol azeotrope ammonia
Hello all, long time viewer first time posting. Can not find the answer anywhere so figured this is the best place for help...
Does methanol form an azeotrope with ammonia? If so, what is the concentration?
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fledarmus
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I haven't seen that combination listed as an azeotrope anywhere, and I would seriously doubt that it could form an azeotrope. The possibility of
forming an azeotrope is dependent on two factors - the deviation of the components from an ideal liquid and therefore from Raoult's Law, and the
difference in boiling points between the two liquids. The chances of forming an azeotrope are best when you have a large deviation from an ideal
liquid (strong intermolecular forces) and a small difference in boiling points. Both methanol and ammonia should show at least some deviation from
Raoult's Law (Ewell classified them both as "Class II" liquids - not as deviant as water but some deviation), but their boiling points are very
different (65C vs -33C)
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Noob I am
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Good info, thanks.
The reason that I thought ammonia may come over with the methanol is because methylamine comes over with methanol in about 8% solution. But the
boiling points of those 2 is much closer.
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BromicAcid
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What about, I don't know, hydrogen chloride (BP -85°C) and water (BP 100°C) for example? All the hydrohalic acids have great descrepancies between
the boiling points of the constituents and still form tenacious azeotropes. As for your second point remember that there are minimum boiling
azeotropes with little interaction, even occuring between immisicble liquids and positive boiling with strong interactions so I wouldn't consider a
deviation from an ideal liquid to point strongly either way. Nevertheless, my azeotrope tables do not list a MeOH / NH3 azeotrope and additionally
list EtOH / NH3 as a non-azeotrope so your conclusion is nonetheless correct.
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Nicodem
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I don't think the original poster is asking about azeotropes. It looks more like he does not know what an azeotrope is and what he is actually asking
is if ammonia can distil with methanol. Of course it can, but the concentration in the distillate depends on the efficiency of the distillation column
used and various other factors (even things like the apparatus geometry and temperature of the cooling water).
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