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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How does freezing of ideal solution actually happens?
I tried thinking on how the ideal solution of a non-volatile solute and volatile solvent would freeze but I can't get to an conclusion. For simplicity, I will consider the solvent to be water here.
I ...
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Why does the pressure sharply increase when the liquid/vapor equilibrium becomes only liquid?
From the US National Chemistry Olympiad:
A sample of a pure substance is placed in a sealed, rigid
container and the pressure is measured as a function of
temperature. Which is the best explanation ...
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In a perfect vacuum, shouldn't every solid be above its sublimation point, since its vapor pressure must exceed the atmospheric pressure?
If the sublimation point of a substance is the point where its equilibrium vapor pressure exceeds the pressure of the atmosphere upon it, and if every solid above absolute zero has some vapor pressure ...
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Why doesn't the vapour pressure exceed the external pressure as boiling begins?
Boiling point is the temperature at which the vapour pressure equals the external pressure and it becomes possible for a bubble to form without getting squeezed and allows it to rise to the surface of ...
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Phases in equilibrium and not in equilibrium
What is the difference between the phases of a substance in equilibrium or not in equilibrium? For example, at room temperature, water is a liquid. It is also a vapor above the liquid formed from the ...
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Why do azeotropes behave the way they do?
I read this answer to a similar question whilst it proved to be plenty insightful there was this one point I failed to understand:
To get a minimum boiling azeotrope, the deviation from Raoult's Law ...
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How do I create a highly conductive vapor cloud [closed]
I'm working on a project that requires that I create an electrically conductive gas cloud that can conduct voltages as low as 1.5v from a regular double A battery. I've been looking into using mecury ...
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Total pressure of saturated solution of air and Benzene [closed]
The question asked for me is - A sample of air is saturated with benzene (vapour pressure =100 mm Hg at 298 K) at 298 K, 750 mm Hg pressure.If it is isothermally compressed to one third of its initial ...
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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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Vapor Pressure of Two Immiscible Liquids [duplicate]
The vapor pressure of two immiscible liquids (A and B) is the sum of their vapor pressures in their pure liquid form.
Intuitively, I don't see how this is possible. If the liquids are being stirred ...
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How do solutes affect the vapour pressure of solutions?
If a non-volatile solute is added to water it will reduce vapour pressure as some space is occupied by non-volatile solute. But what if the solute density is higher than water? Does vapour pressure ...
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What is the exact definition of isotonic solutions?
Background of the Question
I am a high school student so maybe my understanding of this topic is quite less, so apologies in case I have asked an elementary question.
My chemistry sir taught that :-
...
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How is lowering in vapour pressure a colligative property?
Imagine we have two containers: A and B. Both contain equal amounts of water and we add (say 50) molecules of sucrose and 50 molecules of glucose in containers A and B respectively.
Now, the typical ...
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Why doesn't vapour pressure depend upon the amount of liquid?
I was reading about the Clausius-Clapeyron Equation, which is as follows:
I was also reading about Vapour Pressure, when I learned this:
The vapor pressure of a liquid does not depend on the amount ...
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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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Bubbling air through hydrochloric acid to generate HCl gas
I am trying to build a system to generate dry HCl gas. I was wondering if you bubble air through diluted HCl will it produce a gas with mostly water vapor or HCL vapor, can we vary the proportions of ...
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Vapor / liquid balance in a closed container? [closed]
How is the vapor-liquid balance in a closed container computed as a function of temperature? In other words, if I have a container half full of water and I heat the container from 20-degrees C to 30-...
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Why is the relationship between vapour pressure and boiling point of water non-linear?
From my rudimentary understanding of chemistry, pressure should be directly proportional to temperature for a constant mass of gas under the same volume (Charles’s law).
However, in the diagram above,...
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How does steam distillation work to extract a substance from a mixture, below its boiling point?
This is a small confusion I have regarding steam distillation. Let us consider a sample of water mixed with an organic compound that is insoluble in water. Let us also consider that the boiling point ...
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Why is octane more volatile than water while having a higher boiling point?
Octane has a boiling point of 120 °C. Water has a boiling point of 100 °C. The definition of boiling point is, "the temperature which the liquid substance's saturated vapor pressure equals the ...
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Safety of an organic solvent in a sealed pressure pot or vacuum chamber
I am trying to experiment and find ways I can reuse various types of thermoplastics at home for hobby use and have investigated various solubilities of them in solvents (room temp or otherwise) to ...
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THF-H2O mixture at 80°C? isn't THF supposed to evaporate completely?
I was running a synthesis of TiO2 nanoparticles starting from a aqueous solution of TiCl4 2THF 0.125M at 80°C. Through a different experiment it was detemined that the maximum reaction yield was 96% ...
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Why don't P graphs contradict Raoult's law graphs?
Our teacher gave us the following question:
1 mole each of liquids A, B are mixed in a piston-type vessel and piston is moved slowly and isothermally. (PA0 = 75 torr and PB0 = 25 Torr)
Find:
(a) ...
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Explanation for Raoults Law
The vapour pressure of pure liquids is independent of quantity of substance.
But when in a solution, the vapour pressure of the components are given by
$$P_A=P^°_AX_A$$$$P_B=P^°_BX_B$$
Since $A-A$, $A-...
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Vapor pressure of a weak acid for a solution of its salt
I need to calculate the vapor pressure of an acid in equilibrium with an aqueous solution of its salt. For example, say I have a solution of 40% potassium formate by mass in water at 50°C. How do I ...
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Effect of pressure on the vapour pressure of a liquid
In a textbook I am referring to, there is a section on the effect of external pressure affecting the vapour pressure of a liquid.
Source: A Textbook Of Physical Chemistry Volume 3 - KL Kapoor - ...
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Why causes the curvature of the line in pressure-composition graph?
I have been studying about liquid solutions and came across these graphs.
From the first graph it is evident that the solution considered has been assumed ideal as there is no deviation from ideal ...
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How can I find vapour properties of a compound molten salt?
I'm carrying out thermal-hydraulic simulations of the Aircraft Reactor Experiment (a nuclear molten salt reactor) based on circulating molten fuel salt: NaF 53 mol%, ZrF4 41 mol%, UF4 6 mol%.
While ...
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How do I go about calculating final temperature of tank draining at saturation?
I am working on calculating pressure in a tank where the fluid is sitting at its vapor pressure. For example, imagine a 12 in diameter 100 L tank of nitrous oxide at room temperature (745 psi vapor ...
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Explaining Vapour Pressure and Evaporation by Chemical Potential
According to the coexistence curves, both gas and liquid phases can only exist when the chemical potential of both phases are equal.
Does this mean above and below the coexistence curve of liquid and ...
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Why does the vapour pressure not depend on the surface area and volume of a liquid?
My teacher said that vapour pressure is independent of the surface area and volume of a liquid. But I think it should be dependent, because surface area is directly proportional to the evaporation ...
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Understanding how evaporation works [closed]
I am struggling to grasp the concept of partial pressure and vapor pressure.
Consider a sealed container filled with water and a bit of air that is sufficiently dry placed in a room of temperature 25 ...
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What happens to the air pressure above water as its heated to and past boiling?
If I put a pressure sensor inside an airtight container half-filled with water, and heat the water, what will the pressure sensor read as the temperature increases? Would it linearly increase (black ...
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Is it easier to produce hydrodynamic cavitation in a liquid close to boiling point?
Cavitation is defined as the process of formation of the vapor phase of a liquid when it is subjected to reduced pressures at constant ambient temperature. Thus, it is the process of boiling in a ...
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How does the Szilard-Einstein refrigerator design evaporate its refrigerant?
In their 1927 patent, Leo Szilard and Albert Einstein use butane as a refrigerant in their non-compressive refrigerator design. In the patent the authors begin the description of the principle of ...
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Why are the vapor pressure of toluene and benzene different?
We learnt to apply Raoult's law for the ideal solutions. When the questions are asked, they tell that the intermolecular forces of toluene and benzene are equal. But in the same question, they provide ...
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what's the difference between gas and vapour? [duplicate]
In the lecture, our teacher said that the significant difference between gas and vapour is we can't liquefy gas just by compressing it but it's not the same in the case of vapour."
So, I'm ...
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The vapour density of $N_2O_4$ at certain temperature is 30.Calculate the percentage of dissociation of $N_2O_4$ at this temperature? [closed]
The vapour density of $N_2O_4$ at certain temperature is 30.Calculate the percentage of dissociation of $N_2O_4$ at this temperature.$\ce{N2O4_{(g)} <=> 2NO2_{(g)}}$?
I am unable to understand ...
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Suitable solvents to dissolve Aluminum Chloride (anhydrous) without generating Hydrochloric Acid (aqueous or gas)
Hypothetically, I have a chemical tank that was brought out of service and the solid deposits at the bottom of the tank primarily contain aluminum chloride. The whole system never sees water, and the ...
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What is the flash point of acetylene?
On episode s10e11 of the show Criminal Minds, a confrontation occurs in a freezer full of acetylene gas. In this confrontation, the main character confidently fires her gun because the freezer was &...
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What is the nature of container when talking about Boiling Point of a Liquid [ Vapour Pressure related ]? [closed]
From what I understand, whenever talking about calculating the value of Vapour Pressure we need to take a closed container as there needs to be an equilibrium established {R evaporation = R ...
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In a liquid-in-glass thermometer, how does the gas pressure over the liquid affect the linearity of measurement?
In a common ethanol thermometer, the space above the alcohol column is filled with nitrogen. It also contains varying amounts of the alcohol in the gas phase.
Source: http://www.aashtoresource.org/...
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Is vapour pressure truly a colligative property?
Colligative properties are generally defined as
A colligative property depends only on the ratio of the number of particles of solute and solvent in the solution, not the identity of the solute.
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Does the boiling point of ammonia hydroxide change with the ratio of water to ammonia?
My kids and I are designing a science experiment and we could use help with the ratio of water to ammonia in an ammonia hydroxide mixture.
A little bit of background:
Initial goal: To convert the ...
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Calculating the amount of water condensed when cooling below the dew point
I've been given the following question:
Calculate the dew point temperature of a 60% humid air at $30^oC$. How much water mass wil condensate out of 1 $m^3$ of such air when the temperature is ...
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Pressure and temperature relation of Novec 1230
I am working on a concept turbine for a school project which operates at low temperature so it's necessary for me to have a pressure temperature relation of this chemical or novec 7100 also is okay.. ...
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Are molecules exchanged between a solid and liquid in equlibrium?
In Vapor-Liquid Equilibrium, it is my understanding that molecules exchange between the gas and liquid continuously; even when no difference in temperature or partial pressure exists.
Regarding Solid-...
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Mathematical models of Vaporization-Condensation dynamics
I am a mathematician now studying an introductory chemistry course.
Consider a liquid in a closed container, at (say) room temperature.
Then some of the liquid will vaporize. Then some of the ...
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Vapor-Liquid Equilibrium and partial pressure of ammonia
I tried searching the forums for a similar question but I do not think it was entirely answered:
Suppose I have a closed system in a container with solvent and a certain concentration of gas, say ...
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How do water vapor molecules push other air molecules away?
I've read that when water vapor enters the atmosphere, the vapor molecules push the oxygen and nitrogen molecules out of the way and occupy their space.
But if water vapor molecules are lighter than ...
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