Physical state given the critical temperature and critical pressure

In summary, the conversation discusses the use of the Antoine equation to find the saturation pressure of two substances, H2O and CH3OH, at a given temperature and pressure. The speaker also mentions they are having trouble finding the correct scale on a phase diagram to locate the point. They suggest using a log scale to plot the pressure.
  • #1
A13235378
50
10
Moved from a technical forum, so homework template missing
Summary:: 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. 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.
 
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  • #2
You will have to provide a more complete description of the problem you are trying to solve.
 
  • #3
A13235378 said:
Summary:: 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. 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.
Have your graphics package plot the pressure on a log scale.
 

1. What is the critical temperature?

The critical temperature is the temperature at which a substance transitions from a liquid to a gas phase at the critical pressure. Above this temperature, the substance cannot exist in a liquid state regardless of the pressure applied.

2. What is the critical pressure?

The critical pressure is the minimum pressure required to liquefy a gas at its critical temperature. At this pressure, the substance exists in a state where the liquid and gas phases are indistinguishable.

3. How does the physical state change at the critical temperature and pressure?

At the critical temperature and pressure, the substance exists in a state known as the critical point. At this point, the substance has properties of both a liquid and a gas, and there is no clear distinction between the two phases.

4. What happens if the temperature or pressure is above the critical point?

If the temperature is above the critical point, the substance will exist only in a gas phase regardless of the pressure applied. If the pressure is above the critical point, the substance will exist only in a liquid phase regardless of the temperature.

5. How is the critical temperature and pressure determined?

The critical temperature and pressure are determined experimentally by observing the behavior of a substance as temperature and pressure are varied. The critical point is where the substance undergoes a phase transition from a liquid to a gas, or vice versa, and the critical temperature and pressure can be calculated from these observations.

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