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Topic: Azeotrope  (Read 258 times)

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Offline cogujada

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Azeotrope
« on: December 01, 2021, 07:49:29 AM »
Hi, i have a doubt about azeotropes and the y x diagram.
We all know about the y x diagram of a normal binary mixtures, for example from MeOH and Water:



My doubt is when we have a binary mix which has an azeotrope (like EtOH and water), how does the y x diagram looks like (option A or Option B)


Offline mjc123

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Re: Azeotrope
« Reply #1 on: December 01, 2021, 10:20:09 AM »
I am not familiar with this form of "y x diagram", but I assume the straight line gives the liquid composition and the curve gives the composition of the vapour in equilibrium with it at its boiling point.

For a mixture like ethanol-water, consider a mixture with ethanol content lower than the azeotropic composition. Will the vapour have a higher ethanol content than the liquid, or lower? What about a mixture with ethanol content above the azeotropic composition?

Offline Corribus

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Re: Azeotrope
« Reply #2 on: December 01, 2021, 10:49:30 AM »
There is literally no time ever when you should present a plot without properly labeled axes. Each axis label should include what the axis corresponds to and what the units are. Without this information a plot has no meaning.

Here you are plotting moles of methanol versus moles of methanol? This makes no sense to me. Something is missing from your axis labels or your description of what the axes refer to.
« Last Edit: December 01, 2021, 11:11:29 AM by Corribus »
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Offline cogujada

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Re: Azeotrope
« Reply #3 on: December 01, 2021, 02:44:30 PM »
I am not familiar with this form of "y x diagram", but I assume the straight line gives the liquid composition and the curve gives the composition of the vapour in equilibrium with it at its boiling point.

For a mixture like ethanol-water, consider a mixture with ethanol content lower than the azeotropic composition. Will the vapour have a higher ethanol content than the liquid, or lower? What about a mixture with ethanol content above the azeotropic composition?

It is a diagram where the y axis represents the mole fraction of the vapour (MeOH in the first graph and EtOH in the last two graphs) and the x axis represents the mole fraction of the liquid. Above the curve, we have vapour, between the curve and the diagonal line we have equilibrium vapour + liquid, and bellow the diagonal line we have liquid. Hope you understand it ...

Offline cogujada

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Re: Azeotrope
« Reply #4 on: December 01, 2021, 02:46:47 PM »
There is literally no time ever when you should present a plot without properly labeled axes. Each axis label should include what the axis corresponds to and what the units are. Without this information a plot has no meaning.

Here you are plotting moles of methanol versus moles of methanol? This makes no sense to me. Something is missing from your axis labels or your description of what the axes refer to.

True, sorry, I have a lot of work. The first graph it does have labels (but in Spanish, my native tongue). The y axis is molar fraction of MeOH (vapour) and the x axis is molar fraction of MeOH (liquid). The other two graphs do not have labels (sorry for that, mea culpa), but in the y axis we have molar fraction of EtOH (vapour) and on the x axis molar fraction of EtOH (liquid) on both the two bellow graphs. Thanks...

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