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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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 ...
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Calculating the mass of water removed by air conditioning condensation

I cannot figure out how to calculate the mass. The question is: "Suppose the percent relative humidity is $\mathrm{80.0\%}$ at $\mathrm{91.4\ ^\circ F}$ ($\mathrm{33.0\ ^\circ C}$) in a house ...
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How does grease become airborne?

When cooking in the kitchen you usually use some oil or butter to bake your meat and potatoes in. After some weeks without cleaning (which happens every now and then) the surroundings of the stove ...
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368 views

Does benzene vapor react with air in a closed barrel?

If we would have benzene in a closed barrel for quite a while at room temperature, some vapor would form fast due to its volatility, right? But let's say that when the barrel was closed, some air got ...
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Change in volume of two beakers on reaching equilibrium

Two beakers are placed side by side in a sealed container. The first beaker contains 100 ml of pure water. The other an equal volume of an aqueous solution of sugar. What should be the volume of the ...
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Does storing a hygroscopic reagent in a bottle makes it prone to absorb humidity from the air trapped inside?

I've got a full bottle of 99,5% acetone, which I'd really like to keep it as dry as possible, though without using molecular sieves or other dessicants. Once I open the bottle for the first time, use ...
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446 views

Condition for formation of azeotropes

Consider a binary azeotropic solution of two volatile components $A, B$. I wanted to try and find out the required concentrations of $A, B$ in the solution in terms of their vapour pressures. I tried ...
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80 views

Depression of the Freezing Point

Recently we learnt that there is a depression in the freezing point when a non-volatile solute is added to the solvent. Our teacher explained this phenomenon with a graph where the vapour pressure of ...
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288 views

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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Is using melting/boiling point good to measure volatility?

I wanted to figure out a way to compare volatility in organic compounds, so I read on many forums on the differing ways to measure volatility, which included enthalpy of vaporization and melting/...
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Relative humidity and vapor-pressure in equilibrium

I have quite an unclear understanding of relative humidity. I am writing my understanding on the topic and please correct me wherever I'm wrong: What I understood: Let's say $\ce{H2O}$ has a (...
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557 views

To calculate total vapour pressure of a solution

Question: 1 mole each of A and B were mixed to obtain an ideal solution of which one mole went to the vapour phase at equilibrium. If $P°_\mathrm{A} = \pu{100 torr}$ and $P°_\mathrm{B} = \pu{900 torr}$...
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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, the ...
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372 views

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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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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At the freezing point, why is the vapor pressure of the liquid phase equal to the vapor pressure of the solid phase?

At the freezing point of a substance, the solid phase is in dynamic equilibrium with the liquid phase. My textbook defines the freezing point of a substance as: "the temperature at which the vapor ...
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172 views

Control the pressure of Hydrogen in a small container without the use of a pressure regulator

I had recently asked this question, and due to the comments and general consensus of safety concerns, I decided to re-ask the question, attacking the problem from another angle. The Problem I need to ...
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Calculate vapor pressure from volume

For a chemistry lab, I'm required to calculate the vapor pressure of some organic solvents... methanol, ethanol, and propanol, in addition to an "unknown" sample of some solvent. In the lab, we were ...
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Vapors of Aqueous solutions

I'm dealing with a common photoresist developer TMAH (tetramethylammonium hydroxide) and attempting to design a vapor sensor for a sealed chamber. Now I havent been able to confirm what exactly is ...
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546 views

At what composition is Maximum deviation from Raoult's law observed?

Raoult's law states that in an ideal binary solution of two volatile components, the partial vapour pressure of each component is proportional to its mole fraction in the solution. A plot of total ...
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Heating of mixture of gases with one gas barely above its boiling point

What happens when mixture of two gases is heated in a closed container? If one gas expands faster than the other and increases pressure of the container enough so that the boiling point of the other ...
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Calculate the mole fraction of component B in this solution? (partial pressures)

The vapour pressure of a pure liquid solvent A is $\pu{0.80atm}$. When a non volatile substance B is dissolved in the solvent, its vapour pressure drops to $\pu{0.60atm}$. Calculate the mole fraction ...
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Applying Raoult's Law to a condensed gas mixture

So, here's the question which I'm having trouble solving : Suppose that we condense a gas mixture. At 25 celsius, what will be the pressure of benzene and of toluene over the obtained liquid. We ...
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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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If gases turn into liquids under pressure, what does carbon dioxide turn into?

Since there is no liquid state of carbon dioxide, what will carbon dioxide turn into when exposed to high pressure?
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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 ...
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Vapour pressure and Raoult's Law

The following question from my textbook assignment reads A mixture contains $1$ mole volatile liquid $A$ ($P_\mathrm A^\circ = \pu{100 mmHg}$) and $3$ moles of volatile liquid $B$ ($P_\mathrm B^\circ ...
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333 views

Could compressed refrigerant be stored feasibly in residential setting?

In Vapor-compression refrigeration, a refrigerant is compressed releasing heat (typically outside a building) and then decompressed in another location, absorbing heat. A residential air conditioner ...
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How to calculate the vapor pressure of water?

$48~\mathrm{l}$ of dry $\ce{N2}$ passes through $36~\mathrm{g}$ $\ce{H2O}$ at $300~\mathrm{K}$, and this results in a water loss of $1.20~\mathrm{g}$. The vapor pressure of water is? The solution ...
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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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636 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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Help me proving Dalton's law of partial pressure formula

How do I prove $${{\displaystyle p_{i}=p_{\text{total}}y_{i}}}$$ where $y_i$ is the mole fraction of the $i^{th}$ component in the total mixture of $n$ components ? Here is what I know ...
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Is it correct to say that SOME iodine undergoes sublimation at 1 ATM

The triple point of Iodine occurs at 0.12 atm and at standard temperature it is a solid on the phase diagram. I understand that therefore, when heating iodine at 1 atm, it (at least some of it) will ...
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What is the lowest temperature tungsten starts sublimating at?

What is the lowest temperature tungsten starts sublimating at? I've tried to search in Google but without any luck. For example, $\ce{WO3}$ starts sublimating roughly at $\pu{550 °C}$, according to ...
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What is the connection between vapor pressure and intermolecular force explanations of boiling?

I've had boiling explained to me in two ways, and I'm having trouble understanding how they connect. The first way is that a liquid is held together by the intermolecular forces, and boiling involves ...
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Partial pressure of gases in a container with a piston

I've been having problems with the following problem. Figure 1. A container with a piston like that shown in Figure 1 is filled with $0.10$ $mol$ of Ar and $1.00$ $mol$ of water (liquid and vapor). ...
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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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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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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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497 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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Why does the crystal sublime more quickly at the corners where there is a higher vapour gradient?

The crystal responds to the larger vapor gradients near the edges by sublimating faster there and thus rounding the crystal. J. Nelson, J. Atmos. Sci., 1998, 55, 910-119. The change in shape ...
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Relationship between surface area and vapor pressure

How is vapor pressure independent of the surface area and volume of a liquid, although rate of evaporation depends on surface area? Please someone help me I am totally confused.
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Rocket propellants: accuracy of vapor pressure estimation techniques

I would like to determine the vapore pressures of a couple of substances (rocket propellants) over a significant temperature range within a ~10% error margin. For a first test, I tried to ...
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Using vapor mole fraction and pressure to determine liquid mole fraction

I am studying Chemistry by Zumdahl and Zumdahl (9th edition) and I have come across a question in Chapter 11 that I can't figure out the explanation for: Liquid A has vapor pressure x , and liquid B ...
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How to arrange substances in order of increasing vapor pressure?

During the lecture in my chemistry class, my teacher posed the following problem: Arrange in terms of increasing vapor pressure: a) $\pu{0.5m}$ sugar b) $\pu{0.5m} ~ \ce{NaCl}$ c) $\pu{2m}$ ethylene ...
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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 ...
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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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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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Determining the amount of water to create a given pressure in a sealed container

I have a sealed container with a volume of 1 liter. I want to go from an initial pressure of $P_{1}=1\ \mathrm{atm}$ and an initial temperature of $T_{1}=298\ \mathrm{K}$ to a final pressure of $P_{2}=...
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Can different components show different deviations from Raoult's law?

Introduction: Raoult's law is used to calculate the partial pressures of the vapour phases of volatile components of a solution Given that there are two components, A and B, in the liquid-liquid ...