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 rate of vapor formation in binary solutions

If we mix two liquids,one with a vapor pressure of pure liquid 100 torr and other 900 torr ..can we say that for every one mole of the first liquid which vaporizes correspondingly nine moles of the ...
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Physical significance of vapor pressure of pure liquid [on hold]

What exactly is the significance of vapor pressure of a pure liquid(the one used in Raoult's Law)? Does it take into account the pressure exerted by the liquid on the walls of the container also or is ...
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71 views

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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63 views

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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36 views

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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1answer
39 views

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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34 views

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 ...
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Volume change in positive deviation from Raoult's Law

Let us take a mixture of ethanol and acetone as an example. When ethanol is mixed with acetone, the hydrogen bonding between ethanol molecules gets disturbed as actone molecules get in between the ...
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1answer
103 views

what is actually supercritical fluid? [duplicate]

let’s take an example: if we have a glove-box filled with helium at 5 bars at room temperature which is far beyond its critical point, what actually it would be like ? would it be like a normal gas ? ...
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Calculate Gibbs energy of dinitrogen pentoxide using its vapor pressure and sublimation

I am having trouble with the following problem: Dinitrogen pentoxide, $\ce{N2O5}$, is a solid with a high vapor pressure. Its vapor pressure at $\pu{7.5 °C}$ is $\pu{100 mmHg}$, and the solid ...
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41 views

vapor pressure of one part of binary compound

Let's say we have a binary compound AB in an enclosed container, and let's say there's a tendency to form B-vacancies so that B atoms/molecules escape and form a vapor. Let's assume there's enough of ...
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vapor pressure and elevation clarification

I’m a bit confused on why higher elevations/decreased atmospheric pressure wouldn't affect the vapor pressure of a liquid-or have a negligible affect on vapor pressure. With decreased atmospheric ...
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59 views

Can a solid have a vapor pressure without the ability to sublimate?

Does sublimation occur when a solid turns into a gas and THEN vapor pressure is produced or does the solid first have a vapor pressue and then when the vapor pressure of the solid equals the ...
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1answer
206 views

Can ideal gas law be applied to water vapour? [closed]

How to accurately estimate the molar concentration of pure water vapour at 298 K? Can ideal gas law be applied to water vapour to calculate the molar concentration?
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Boiling of a liquid [duplicate]

Consider water as an example. I m really confused when does boiling takes place. When it's vapour pressure equals atmospheric pressure or when it's saturation atmospheric pressure equals atmospheric ...
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1answer
33 views

Boiling temperature of salt water at low pressure

With a hydro aspirator with re-circulating water (see here), the maximum vacuum you can get is set by the water vapor pressure given the temperature. Can you lower the vapor pressure measurably by ...
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143 views

Entropy as the driving force for osmosis

How is entropy responsible for osmosis and is movement of solvent possible from its higher concentration to lower concentration? By concentration, I will be referring to the concentration of solvent ...
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Reason for formation of bubbles at boiling point [duplicate]

As I understand it, boiling takes place when the saturated vapour pressure equals to the atmospheric pressure. But, why does the vapour pressure need to be equal to the atmospheric pressure for ...
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345 views

Why does freezing point decrease when vapour pressure decreases in dilute solutions?

I was studying colligative properties of dilute solutions, and one of the properties was freezing point depression. The confusion I had was that, if vapour pressure decreases, it should be easier to ...
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Is it true that an evaporating molecule has the same kinetic energy as a molecule in a pot of boiling water?

A molecule on the surface of room-temperature water shoots off the surface of said water, or in other words, it "evaporates." It does so because it gained kinetic energy ${x}$, and ${x}$ was great ...
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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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1answer
54 views

Double surface in the pressure temperature concentration curve for a binary mixture

In the 3 dimensional diagram given, when a constant pressure plane intersects with the double surface, it produces a looped curve without a maxima or minima. What is the double surface and how is the ...
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1answer
265 views

Why is the equilibrium constant of water with its vapour equivalent to its vapour pressure?

Can someone conceptually explain why the equilibrium constant is equivalent to the vapour pressure of water for the above equilibrium reaction? For example if $K = x$, then it is said that vapour ...
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1answer
45 views

Can air inside a high temperature (1300C) Kiln cause an explosion?

I saw many kiln designs that lack an opening for hot\pressurized air to come out , or any pressure valve. But when air is heated to such a high temperature (1300C) inside a closed chamber (the kiln), ...
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53 views

High vapor pressure cooking

On a Wikipedia article about latent heat, it can be found: The large value of the enthalpy of condensation of water vapor is the reason that steam is a far more effective heating medium than ...
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Thermodynamics energy balance question help

I made the following attempt to solve this question.However I don't know how to find final pressure.I don't know how to find final temperature for both sides.Can you give me a hint?
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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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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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116 views

Does Langmuir model predict evaporation rates?

Slide #16 of this presentation on amalgams says that "Langmuir's equation" provides a specific "theoretical maximum evaporation rate" for liquid Hg as a function of temperature and surface area. The ...
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76 views

When boiling a liquid, how vapour pressure and ambient pressure get equal? [duplicate]

When boiling a liquid, how vapour pressure and ambient pressure get equal? As vapour pressure will increase, it will lead to increase in ambient pressure also. let, Initially there would be some ...
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Acetic acid odor while testing CO2 sensor; can it be easily removed, is there a better way?

A friend asked me to help test a hobby-quality $\ce{CO2}$ sensor MG-811 (updated link). It uses a solid electrolyte and should provide a sensitivity of something like -40 mV per decade. I though I'd ...
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1answer
74 views

Vapor Pressure, Equillibrium, and Increasing Pressure

I'm trying to make sure my understanding of vapor pressure and transients is correct. Let's assume I have a thermally-controlled sealed environment which started out as the regular air (i.e. ...
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A chamber to control concentration of a vapor: Is there a name for this equipment?

Mechanical engineer here so please excuse me if my question seems dumb to you! I want to have a chamber $(\approx 40 \times 30 \times \pu{30 cm})$ to control concentration $(\pu{ppm})$ of a flammable ...
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Inquiry of the Changing of Canned Liquid’s State [closed]

Could you heat a can of water to 212 degrees Fahrenheit but stay below the aluminum or the can’s metal’s melting point. Either through putting the can in boiling water or heating it up. Would it be ...
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367 views

What is the relation between pressure and chemical potential?

I know that in a two-component gas-liquid system (for simplicity) the chemical potential $\mu_i$ ($i=1,2$) and total pressure $p$ can be defined by $$\mu_i=\left(\frac{\partial U}{\partial N_i}\right)...
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Is my proof valid for the formula of elevation in boiling point? [closed]

Is my proof valid for the formula of elevation in boiling point? proof By Clausius clayperon equation, $$\ln(P)=-\frac{∆H_v}{RT}+c$$ Differentiating, $$\frac{dP}{...
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Why does only a single azeotropic composition exist for a mixture of two given substances?

In the image below, which represents a generic composition vs. temperature plot for a mixture, there is a single intersection point between the vapor and liquid curves. This is due to the fact that ...
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498 views

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). ...
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536 views

When heat is increased, does water move upward in a straw due to increased capillary action or increased pressure?

I left a water bottle with an internal straw in my car throughout a long, hot day. When I opened the bottle at the end of the day, water immediately splashed out from the straw. This made me wonder if ...
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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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214 views

Bromine monochloride equilibrium

The value of $K_p$ for the reaction $$\ce{Br2(l) + Cl2(g) <=> 2BrCl(g)}$$ is $\pu{1 atm}$. At equilibrium in a closed container partial pressure of $\ce{BrCl}$ gas is $\pu{0.1 atm}$ and at ...
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100 views

Metals Vapor Pressure [duplicate]

I know metals like copper, silver and gold for example have vapor pressures at high temperature but do their vapor pressures still exist at standard temperatures (290 kelvin) and pressures (100 ...
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550 views

Solution to Raoult's Law for a volatile binary solution (no pun intended)

Raoult's Law In a closed container, $$P_A=P_A^\circ x_A$$ where $P_A$ is the pressure of compound in gaseous phase, and $x_A$ is the mole fraction of the liquid component A in the liquid mixture. If ...