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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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 ...
The Entity's user avatar
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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,...
Yitian Chen's user avatar
2 votes
2 answers
189 views

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 ...
donthababakka's user avatar
14 votes
5 answers
3k views

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 ...
donthababakka's user avatar
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Vapour pressure and Raoults law [duplicate]

Suppose we take a binary ideal solution having components A and B .... let's say that their mole fraction is 1/3 and 2/3 respectively (for simplicity) Now ... We know that this solution will start ...
Daksh Kapoor's user avatar
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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 ...
Nick Perry's user avatar
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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) ...
Arghya Shubhshiv's user avatar
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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 - ...
omega's user avatar
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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 ...
BlueInfinite1729's user avatar
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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 ...
Ruggero Rosselli's user avatar
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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 ...
Alexander Patrus's user avatar
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1 answer
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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 ...
omega's user avatar
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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 ...
Rohan Singh's user avatar
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1 answer
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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 ...
Ray Siplao's user avatar
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1 answer
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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 ...
Oliver Walters's user avatar
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1 answer
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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 ...
Oliver Walters's user avatar
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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 ...
cms's user avatar
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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 ...
Chamodh Nethsara's user avatar
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1 answer
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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 ...
anonymous's user avatar
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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 ...
Sam's user avatar
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2 answers
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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 &...
thepenguin77's user avatar
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1 answer
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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 ...
Paras Gupta's user avatar
9 votes
1 answer
353 views

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/...
Karsten's user avatar
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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 ...
thefiddler's user avatar
2 votes
1 answer
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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 ...
DannyBoy's user avatar
0 votes
1 answer
122 views

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.. ...
Doctor Pinocchio's user avatar
10 votes
1 answer
828 views

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-...
ericnutsch's user avatar
2 votes
1 answer
77 views

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 ...
Asaf Shachar's user avatar
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0 answers
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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 ...
bkrish's user avatar
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3 answers
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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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3 votes
1 answer
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Can vapor pressure be defined for permanent gases?

Vapor pressure of a substance, in a given temperature, is the pressure exerted the vapor in a system where the gaseous and liquid phases of the pure substance are in equilibrium. But, if for a ...
user2934303's user avatar
0 votes
1 answer
489 views

How do you derive the boiling point elevation equation using Raoult’s law and Clausius-Clapeyron relation?

I know that Raoult's law is $P_{solution}=X_{solvent}P_{solvent}$ and Clausius-Clapeyron equation is $ln(\frac{P_{2}}{P_{1}})=-\frac{L}{R}(\frac{1}{T_{2}}-\frac{1}{T_{1}})$ But how do you derive the ...
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Saturation of air within isolated system with water and ethanol

I am planning an experiment in an isolated system that contains two droplets. One droplet is water and the other one is a 40% ethanol-water mixture. The isolated compartment is filled with air at 20°C....
schnoedroeboenick's user avatar
1 vote
1 answer
101 views

Why does Raoult's Law have a weighted sum instead of a direct sum?

I'm fully aware of the various questions asked about Raoult's Law, and I'm asking this after having gone through all of them and not finding a suitable answer to my question. I have studied, that at a ...
Umesh Konduru's user avatar
1 vote
0 answers
357 views

Interpretation of azeotropes from statistical mechanics derivation

In an earlier posted question titled Reason for the formation of azeotropes, @porphyrin presented an elegant derivation from statistical mechanics to interpret partial pressures for the two components ...
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Saturated vapor and liquid densities (VLC curve) from Helmholtz free energy equation of state

I have been reading about the statistical associating fluid theory (SAFT) which computes the Helmholtz free energy ($A$) from the SAFT EoS (a hell lot of equations) for a molecule of interest, and is ...
physicsnovice's user avatar
1 vote
1 answer
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Do benzene and hexane form an ideal solution?

My teacher said that benzene and hexane do not form an ideal solution (with reference to Raoult's law) but did not explain any reason for it. My approach: Cyclic hydrocarbons (benzene here) have ...
Balu's user avatar
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Pressure increase in a chamber with 1 ml of water heated to 200 °C [closed]

For safety reasons I want to know how much pressure will be generated in a sealed chamber with $1~\mathrm{ml}$ of water, pure nitrogen at $1.3~\mathrm{bar}$ at $22~\mathrm{^\circ C}$. This chamber ...
Lee Smith's user avatar
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1 answer
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What is the ∆H_vap when temperature of a given liquid is equal to the boiling point of the liquid?

What is the $∆H_{vap}$ when temperature of a given liquid is equal to the boiling point of the liquid? For the other cases ie (i) T>BP, $∆H_{vap}$ > 0 (ii) T<BP, $∆H_{vap}$ < 0 So what ...
Snehal Saurabh's user avatar
3 votes
1 answer
163 views

Is there a vapor pressure equivalent to freezing point?

Vapor pressure is where liquids are breaking off into the gas phase, below the boiling point. So is there a term where solids break off into the liquid phase, below the freezing point? Vapor pressure ...
Neal Conroy's user avatar
0 votes
1 answer
451 views

Data on Vapour Pressures of Silicone Oils [closed]

I am trying to find specific information on vapour pressure of silicone oils with different viscosities which I have used in some experimental work. Is there a chemical databook where this information ...
Tom's user avatar
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Vapour pressure and boiling [duplicate]

I have come across two definitions for boiling point: It is the temperature at which a liquid gets vaporised It is the point where vapour pressure = external pressure How are they related? How does ...
Draculin's user avatar
1 vote
1 answer
246 views

Why does boiling occur when vapor pressure equals ambient pressure?

Here is my understanding of the boiling process: pressure of the atmosphere is pressing down on the liquid and this pressure is propagated throughout the liquid. That is, pressure everywhere inside ...
silverbackgorilla's user avatar
3 votes
3 answers
1k views

Some salts lower the vapour pressure of water - do any raise it?

Plain old NaCl salt can slightly lower the vapour pressure of water for a given temperature. Other salts such as CaCl₂ lower the vapour pressure to a larger degree. Do any salts, or compounds of any ...
Aidan Connelly's user avatar

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