# Questions tagged [vapor-pressure]

This is the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phases (solid or liquid) at a given temperature in a closed system. Apply this tag to questions involving clarification related to vapor pressure.

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119 views

### Quantitative Transfer of Volatile Standards

(Edited w/ updates) Okay, long story short I work in a lab which has been working on cannabinoid analysis (in the licensed Canadian market) and have had a lot of issues surrounding the standards/...
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### Cases when Raoult's law is unsolvable

Setup Consider a closed binary mixture of known total molar composition $n_i$, held at volume $V$ and temperature $T$. The equilibrium phase composition is determined by $\mu_i^{vap} = \mu_i^{liq}$. ...
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### Vapor-pressure or Vapor-concentration

To summarize from my textbook: rate of evaporation: proportional to surface area but essentially independent from pressure (of surrounding gas) rate of condensation proportional to both surface ...
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### Can a droplet of formalin evaporate in midair while falling?

I am designing an evaporator for use in an enclosed environment. Due to the hazardous nature of formaldehyde, I want my evaporator to be wick-free. The environment in which the evaporator will be used ...
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### Volume of dried gas at STP

A $54.0\ \mathrm{mL}$ sample of oxygen is collected over water at $20\ \mathrm{^\circ C}$ and $770\ \mathrm{Torr}$ pressure. What is the volume of the dry gas at STP? By using the combined gas law, I ...
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### How does association within vapor or dissociation within liquid affect the ideal nature of a binary solution?

As I understand, when there is positive deviation of a binary solution from Raoult's Law, the equilibrium partial pressure curve approach ideality (i.e a straight line dependence of equilibrium ...
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### What causes both components of a binary gas mix to condensate at the same time for a given composition

Okay, so recently I encountered the temperature - mole fraction diagrams for binary vapour-liquid equilibrium. For now, I only consider two-component systems where the components are very similar and ...
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### Anhydrous ammonia vapor-liquid equilibrium

I have been given a anhydrous ammonia vapor liquid system in an air-tight container where the pressure is 30 bar and the temperature is 30 degrees. They claim the system is in equilibrium, which I ...
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### Predicting the vapor pressure of water ammonia solution

I am working on a project that involves the compressors for a vapor compression refrigeration cycle of R717 (ammonia) and came across something that has been boggling my mind a little bit for no good ...
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### Rate of evaporation of mercury

A restorer of antique barometers reported in a blog post that he has had a barometer on his wall that has shown no "visible" loss of mercury in 15 years. I was kind of curious about this, wondering ...
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### Identifying T1 and T2 in the Claperyon equation

Is there a way to identify T1 and T2 in the two point form of the claperyon equation? I suspect that the greater temperature is T1 and the smaller temperature is T2.
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### how to find pressure of a liquid when given volume (1 and 2) and one pressure?

A 5 mL sample of an unknown liquid is placed into a 250 mL flask that has had all of the air removed. The pressure measured in the flask is found to be 35.4kPa. In a seperate trial the student puts ...
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### Why does melting point depend on external pressure?

The melting point of a substance is the temperature at which the solid form's vapor pressure equals the liquid form's vapor pressure. I read that the vapor pressure of something depends ONLY on the ...
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### Applying Raoult's Law in volatile solids–liquid solutions

My textbook explains applying Raoult's Law for the two cases: liquid–liquid solutions, in which the vapour pressure of the solution is due to both the components non-volatile solids–liquid solutions, ...
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### Why is vapor pressure constant at boiling point?

At non-boiling point, I understand that when you add heat, temperature increases and also the amount of gas increases, so by using $PV=nRT$ at constant volume, the increase in $n$ and $T$ would ...
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### The minima of minimum boiling azeotropes

This is a very basic doubt, so I'll be really brief about it. The discussion I raise is particularly about minimum boiling azeotropes but it's understood that whatever I ask is about the general ...
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### How to compute the pressure potential of the fermentation of sugar into carbon dioxide?

I'm doing an experiment to ferment table sugar with yeast to capture the resulting carbon dioxide. Suppose I put $x$ grams of sugar in a closed 1 liter bottle with yeast. How can I compute the ...
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### Is the evaporation (liquid to gas conversion) of ethanol dependent on how full you fill it up in a sealed bottle?

It seems intuitive to think that in a bottle (which is air-tight), if you fill up ethanol (or any other volatile liquid) to very full extent, thereby leaving very little headspace, the amount of ...
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### Two-Phase Pressure Drops in Screen-Plate Bubble Column

I am reading the paper A Correlation of Two-Phase Pressure Drops in Screen-Plate Bubble Column The goal of the paper is to come up with a regression model for a correction factor (denoted $K$) for a ...
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### Combining two high-VP chemicals to get a low-VP mixture

I'd like to do a class experiment as a metaphor for human relationships. Two people each have a different chemical which evaporates quickly (at STP). There is one glass between them. If only one ...
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### Will evaporation from two immiscible liquids blow up a balloon?

Consider the following setup: Two immiscible liquids A and B are placed inside a balloon at a temperature where neither one of them boils. The inside of the balloon contains some argon, and the ...
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### For azeotropic mixtures, is the total vapour pressure at equilibrium equal to the partial pressure of one of the components?

I know, a ridiculous statement. But here's how I reached at it . Say we have a solution of two components liquids A and B. By Raoults law, $$p_A= p_A^o \times x_A \tag1$$ Also by Dalton's law, ...
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### Water vapor equilibrium calculations

The question had two parts. The first part said: Calculate the amount of water required to saturate a vessel of volume 82 L at 300 K given that the vapor pressure of water is 38 torr at 300 K. The ...
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### vapour pressure above 2 separate beakers containing liquids which form ideal solution

Suppose we have A moles of liquid 1 in one beaker and B moles of liquid 2 in the other. Beakers are placed together in a biger closed container. Both have different vapour pressure when isloated. Now ...
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### Why is the temperature graph sigmoidal in simple distillation of components with very different bps?

I'm writing an organic chemistry lab report on distillation and I thought I understood this, but the more I look at my lab textbook, I realize I don't. My textbook 1 explains that the temperature of ...
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### Vapour Pressure of solutions and mol fractions

From a solution (ideal) which contains the components A and B ,the vapours over the solution at a temperature T are collected and condensed into liquid and again brought to the same temperature T. ...
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### How can I calculate the concentration of ethanol vapor in an airstream?

How can I calculate the concentration of ethanol vapor in an airstream? The steady state generation flow rate (of the vapor) is 625 ft^3/min. The ambient temp is 50-60 F (we can use avg temp 55 F). ...