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### Topic: Physical state given the critical temperature and critical pressure  (Read 266 times)

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#### A13235378

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##### Physical state given the critical temperature and critical pressure
« on: September 07, 2020, 08:33:39 PM »
I have two substances H2O and CH3OH given at a temperature T and pressure P.

I also have critical temperatures and pressures.

How can I find the physical states of these substances.

My teacher recommended me to use the Antoine equation and find the saturation pressure, but I can't see how it can help me.
« Last Edit: September 07, 2020, 09:12:53 PM by A13235378 »

#### Borek

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##### Re: Physical state given the critical temperature and critical pressure
« Reply #1 on: September 08, 2020, 02:43:00 AM »
Phase diagram would be the most obvious approach.

But once you know saturation pressure you can compare it with the given P, don't you?
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#### A13235378

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##### Re: Physical state given the critical temperature and critical pressure
« Reply #2 on: September 08, 2020, 07:00:37 AM »
Phase diagram would be the most obvious approach.

But once you know saturation pressure you can compare it with the given P, don't you?

Yes, I tried it on a phase diagram, but I couldn't find one that would provide the right scale. I can't find exactly where the point is. If you want, I can pass exactly the right values. And when you said that the saturation point could help, do you mean that this point is the same critical point? If not, I am unable to understand the meaning of this saturated pressure, because I calculated using the antoine constants to a temperature fax and did not give the same result as the critical pressure

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