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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Relative humidity at constant temperatures

It’s known that Relative humidity = (water pressure in a certain volume/ saturated water pressure in the same volume)* 100% “at the same temperature” So my question is why does the amount of water ...
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Measuring vapour pressure in a closed system

My experiment requires the determination of vapour pressure from which I will calculate the number density (or number of moles of the molecule) later, for a closed system. Here's my setup : Liquid ...
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Latent Heat and the effect of cooling a liquid when phase transitioning [closed]

So after reading about this topic i wanted to share what i learned and i wanted you guys to tell me if what i am writting is correct: So imagine that some liquefied gas like propane or butane (it is ...
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Explanation for difference in slope of graph of relative lowering of vapour pressure

Can someone tell the reason for the difference in the slope of graph of vapour pressure vs temperature of solid solvent and liquid solvent both the physical (actual process taking place) and ...
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2answers
45 views

Shouldn't the pressure of gas above a liquid slightly decrease when some of its molecules dissolves in the liquid? [closed]

Lets say a liquid and gas above are in equilibrium. (1) Now if I suddenly increase the pressure of the gas it will take some time for some molecules of the gas to enter the liquid and get dissolved. ...
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Cross checking the fact that gas solubility decreases with temperature increase and Henry's law's validity

It is known that the solubility of gas decreases with increase in temperature which is due to the kinetic energy freeing the solute particles into the vapor phase. Henry's law states that the partial ...
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Vapor Pressure and Boiling Point [duplicate]

I heard that the boiling point of a solution is the temperature where its vapor pressure at that temperature equals the atmospheric pressure at that temperature. Thus at higher altitudes, as the ...
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1answer
18 views

Doubt about definition of boiling point [duplicate]

The definition of boiling point says boiling point is the temperature at which the vapour pressure of liquid becomes equal to vapour pressure of atmosphere. But how does the vapour pressure of the ...
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61 views

How is Raoult's law a special case of Henry's law and not vice versa?

I know that Raoult's law can be a special case of Henry's law when the value of the Henry's constant becomes equal to the vapour pressure of the pure state of the liquid. Why can't we say the opposite,...
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How much time liquid mercury takes to evaporate?

I asked before about a thermometer that I broke yesterday. To summarize, I broke a mercury thermometer in my bedroom, which is a place where is difficult to have sure that I get rid of all mercury, ...
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Vapour pressure of a liquid subjected to pressure

I am following the derivation by Atkins in section 4B(c) (Physical transformations of pure substances; thermodynamic aspects of phase transitions), in which the authors derive the equation ${p = p_* * ...
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Algae Cultivation Using Polyethylene Film Reactor Vessel Floating In Pool with Algicidal ClO2 Concentration

I'm attempting to grow chlorella algae in a polyethylene film bag (which contains the growth medium) submerged in a temperature-moderating, above-ground swimming pool. This presents a challenge in ...
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Does evaporation occur while boiling as well? [closed]

If evaporation were to occur when a liquid was being boiled, then the amount of liquid changing phase would also depend on the surface area of the liquid exposed to the atmosphere (as evaporation rate ...
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What is the vapor pressure of a liquid if it is not in a sealed container(i.e., a river or lake)? Is it just the atmospheric pressure? [closed]

From what I understand, the boiling point of a liquid is when its surrounding pressure is equal to its vapor pressure. The vapor pressure is the pressure of the gas form of the liquid in a container ...
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Reducing pressure in a binary liquid solution

Consider the following diagram for a binary liquid system comprised of A and B, where A is the more volatile component. My professor says Consider an isopleth from $a$ to $a_4$. At the start, ...
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Vapour Pressure of A Solution

I study in class 12, and have a doubt in vapour pressure that my school teacher and my friends are not able to clarify. My doubt is the reason why the partial vapour pressure of each individual ...
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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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How to find relative lowering of vapour pressure from phase diagrams in terms of temperature?

Problem Answer My question Does a tie rule exist for solution solvent phase diagram to express relative lowering of vapour pressure in terms of temperature? The phase diagram is the one ...
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Antoine law and ideal gas law

I have the following question: A $100\ \mathrm{ml}$ sealed flask with $60\ \mathrm{ml}$ acetonitrile is heated to $140\ \mathrm{^\circ C}$. The boiling point of acetonitrile is $82\ \mathrm{^\circ ...
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can a vapour denser than air evaporate in a closed chamber? [closed]

Imagine a closed container filled with air. There is some liquid substance on a bottle placed on the floor of the container. Let's heat the liquid until it starts to evaporate. Let's say 20% of the ...
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How do you manage to liquefy a gas by applying only pressure? [closed]

How can you liquefy a gas by applying only pressure? To increase the pressure of a gas you need a compressor, and when the compressor does work on the gas , it will increase his pressure but at the ...
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What happens with the boiling point of a liquid in a vacuum [closed]

This may be a silly question, but when I was reading my chemistry textbook, there was this following statement: "A liquid boils when its vapor pressure equals the external pressure acting on the ...
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Is this example considered liquifying a gas under pressure?

In my work place, we have a drum that has propene inside at a pressure of around 2,5 bar and at a temperature of around -15ºc and the boil-off of that drum is aspirate by a compressor and is ...
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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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Is it possible to find the volume of condensed water by temperature change without knowing the initial pressure of the flask?

I found this problem in a practice sheet. The original source doesn't indicate any authorship or whatsoever. It states the following: A sealed container of $\pu{6.24 L}$ in capacity has humid air ...
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Why is so different the temperatures of a compressed gas compared to a liquid/gas mixture of the same fluid and they are both at the same pressure?

Why does $\ce{C3H6}$ gas when compressed (in a centrifugal compressor) comes out with a pressure of $\pu{16 bar}$ and $\pu{90 °C},$ and when it is a mixture of $\ce{C3H6}$ liquid/gas stored inside of ...
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Is there any non-toxic and non-solvable-in-air liquid? [closed]

I want to heat the air with non-aqueous, non-toxic and non-solvable-in-air liquid (with very low relative pressure in air). Is there any such liquid exists? It would be great if the boiling point of ...
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Why is latent heat of vaporization not exactly proportional to boiling point?

Latent heat of vaporization and boiling point are both chemical properties related to the bond strength of the molecule. In general, the higher the boiling point is, the higher the heat of ...
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The relationship between the temperatures at different times and pressures at different times is? [closed]

At the instant the boiling point is reached, the vapour pressure of the solution should be equal to atm. pressure. And since the boiling is continued the pressure will keep on increasing. Thus the ...
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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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Volatile alkali metal compounds

Most elements are or have compounds that are gases or have a significant vapor pressure at room temperature. Fluoride is a powerful tool for producing highly oxidized covalent and volatile compounds. ...
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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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Is the vapor pressure of a liquid dependent on the pressure of the atmosphere in which it is measured?

The figure below shows how vapor pressure of a liquid is measured. Initially the flask is at atmospheric pressure. Then the liquid is dropped in the flask. Once equilibrium is reached, the pressure ...
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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 vs. ambient pressure

I've managed to get myself thoroughly confused in thinking about the vapor pressure of a substance at a particular temperature $T$, and how it relates to the pressure of the substance if it is in a ...
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How to find the Cp, difference of Cp and heat of fusion from the dependence of vapor pressure on temperature?

The vapor pressure of zinc varies with temperature as $$\log P(\pu{mm Hg}) = -6850/T - 0.755\log T + 11.24 \label{eqn:1}\tag{1}$$ and that of liquid zinc as $$\log P(\pu{mm Hg}) = -6620/...
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Liquid solutions and vapour pressure

"The vapour pressure of water at 80° C is 355 torr. A 100 mL vessel contained water-saturated oxygen at 80° C, the total gas pressure being 760 torr. The contents of the vessel were pumped into a 50 ...
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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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Is it possible to have only liquid in a closed container?

I recently read an answer by Aman Rusia for this question: Is a liquid in a container always in equilibrium with its vapour? In it, they say that You can't have a container filled with only ...
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At boiling point, is the total pressure twice the atmospheric pressure? [duplicate]

We know that one definition of boiling point is that it's the temperature at which the vapor pressure is same as the atmospheric pressure. Assuming a closed container, does that mean that at this ...
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Issue with evaporation rate of water

The evaporation rate of water (kg/s) is given by: $$g = \frac{P}{P_o} AΘ$$ Where $P$ is given in Pascals and $A$ is the surface area (in $m^2$) and $Θ$ is the empirical evaporation ...
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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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Microscopic and mechanical approach to boiling point [duplicate]

I am confused as to how I should visualize the boiling process throughout a liquid. From my understanding, the boiling point of a liquid is when its vapor pressure reaches atmospheric pressure. This ...
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Is vapour pressure a surface phenomenon?

As a fact, I know that vapour pressure doesn't depend on surface area. Does this imply it is not a surface phenomenon also? It shouldn't be as then it would depend on surface area of molecules and ...
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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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Is it possible to boil a liquid by just mixing many immiscible liquids together?

In open air, when vapour pressure reaches 1 atm, boiling takes place. I read that if we add two immiscible liquids together, the total vapour pressure of the 'mixture' is close to $p = p^*_A + p^*_b$,...
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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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Question about liquid-phase in P-T Diagram

Currently, I have been learning about P-T diagrams and vapour pressure and I have a question that seems like it should have a simple explanation yet I am not able to understand it. Taking the P-T ...
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Is 99% Isopropyl Alcohol sold in stores really 99%?

My understanding is that an azeotropic mixture of isopropanol and water is 91%. This makes sense as to why there are so many brands of rubbing alcohol sold at 91%. There are also some sold as 99%, ...
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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 ...