# Questions tagged [phase-diagram]

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### Why do we have water vapor at room temperature and atmospheric pressure when water is a compressed liquid at these conditions?

At room temperature and 1 atm pressure liquid water should be a compressed liquid. Now if that is the case then why do we have water vapor at these conditions? I can't make sense of this based on just ...
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### Phase diagram of ammonium hydrosulfide, a volatile salt

Salts (ionic compounds) usually have low volatility due to the strong ionic bond. However, there are exceptions. Smelling salts decompose and release ammonia gas. What is "volatile"? If a ...
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### Do all three states need to be present at triple point?

A recent United States National Chemistry Olympiad question asked the following: Which statement best describes a sample of ammonia at equilibrium at its triple point (195.4 K, 0.0606 bar)? A) ...
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### Interpretation of a Phase Diagram

I am a bit confused about the correct way to interpret a phase diagram. I was told that the line separating the liquid and gas phases gives the vapor pressure of the liquid substance as a function of ...
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### Phase Diagram Vertical Lines

We had to create a phase diagram of H2O and NaCl. My professor mentioned that the vertical line I’ve encircled is at the weight % of 61.9. I was just wondering if this is proven through experiment or ...
1 vote
126 views

### Why do reduced variables for gases use their critical constants?

I understand why it's useful to have reduced variables, especially as it is the basis for the theorem of corresponding states. However, I'm having a hard time understanding why the critical constants ...
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### How salt helps to melt ice even when there is no dynamic equilibrium between water and ice?

I am a high school student and I am confused about freezing point depression. We say that when in winter's it gets even colder than normal freezing point Temperature then we use solute to melt ice ...
1 vote
69 views

### Searching for a phase transition dataset for substances

Disclaimer: I'm not a chemist, just a curious engineer. As per the title, I'm searching for a dataset (or relevant Python library) with phase transition information for different substances. Eg: water,...
1 vote
160 views

### Gibbs phase rule for azeotrope and Solid-Liquid phase diagram

Azeotrope An azeotrope is a mixture of two or more components in fluidic states whose proportions cannot be altered or changed by simple distillation Applying the phase rule to azeotrope. There are 2 ...
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### Enrichment in phase diagram

After my post at UF4-ZrF4 phase diagram (the phase diagram is given below) Question: Consider the coordination (40%; 900oC), the cooling to 850oC would form x(ZrF4) = 0,22. When the cooling ...
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### UF4-ZrF4 phase diagram

I am doing physical chemistry tasks in Professor Peter Atkins book. The phase diagram of UF4-ZrF4 system that I found is in the following picture Question: Where is the point that the composition x(...
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### Is there a supercritical state for ice?

I know there is such a thing as a supercritical fluid, where the vapor and liquid phases are indistinguishable, but is there such a thing as a supercritical state for ice? Another way of asking this ...
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