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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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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3answers
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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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2answers
77 views
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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1answer
51 views
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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63 views
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
94 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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2answers
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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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1answer
39 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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2answers
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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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1answer
54 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
126 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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1answer
56 views
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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1answer
118 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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0answers
56 views
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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1answer
310 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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2answers
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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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0answers
41 views
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
51 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
230 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
40 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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1answer
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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1answer
85 views
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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0answers
70 views
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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1answer
100 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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1answer
71 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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1answer
88 views
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
69 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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1answer
280 views
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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1answer
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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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0answers
325 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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0answers
179 views
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,
$$\frac{dP}{...
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0answers
99 views
Why does only a single azeotropic composition exist for a mixture of two given substances?
In the image below, which represents a generic composition vs. temperature plot for a mixture, there is a single intersection point between the vapor and liquid curves. This is due to the fact that ...
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1answer
455 views
How can I calculate the concentration of ethanol vapor in an airstream?
How can I calculate the concentration of ethanol vapor in an airstream?
The steady state generation flow rate (of the vapor) is 625 ft^3/min. The ambient temp is 50-60 F (we can use avg temp 55 F).
...
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1answer
490 views
When heat is increased, does water move upward in a straw due to increased capillary action or increased pressure?
I left a water bottle with an internal straw in my car throughout a long, hot day. When I opened the bottle at the end of the day, water immediately splashed out from the straw. This made me wonder if ...
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0answers
154 views
Anhydrous ammonia vapor-liquid equilibrium
I have been given a anhydrous ammonia vapor liquid system in an air-tight container where the pressure is 30 bar and the temperature is 30 degrees. They claim the system is in equilibrium, which I ...
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1answer
196 views
Bromine monochloride equilibrium
The value of $K_p$ for the reaction
$$\ce{Br2(l) + Cl2(g) <=> 2BrCl(g)}$$
is $\pu{1 atm}$. At equilibrium in a closed container partial pressure of $\ce{BrCl}$ gas is $\pu{0.1 atm}$ and at ...
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1answer
100 views
Metals Vapor Pressure [duplicate]
I know metals like copper, silver and gold for example have vapor pressures at high temperature but do their vapor pressures still exist at standard temperatures (290 kelvin) and pressures (100 ...
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1answer
512 views
Solution to Raoult's Law for a volatile binary solution (no pun intended)
Raoult's Law
In a closed container, $$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 ...
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0answers
469 views
Predicting the vapor pressure of water ammonia solution
I am working on a project that involves the compressors for a vapor compression refrigeration cycle of R717 (ammonia) and came across something that has been boggling my mind a little bit for no good ...
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1answer
1k views
What would be the vapor pressure of water at above 100 degrees Celsius?
Water boils when it's vapor pressure equals atmospheric pressure (i.e., 760 mm of Hg) which is at 100 degrees Celsius. If the temperature is further increased, would the vapor pressure also increase ...
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0answers
134 views
Alternative to mercury bubbler for increasing boiling temp?
A common reaction for forming the octachlorodirhenate(III) anion is to heat tert-n-butylammonium perrhenate in benzoyl chloride at 209 ºC. If you look up the info for benzoyl chloride, one sees that ...
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2answers
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Vapor Pressure Paradox
This is quite an interesting situation I had thought of. Consider two beakers, each containing $\pu{180 g}$ of water. Also, suppose one of the two has $\pu{1.8 g}$ of glucose dissolved in it. Let's ...
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Water vapor equilibrium calculations
The question had two parts.
The first part said:
Calculate the amount of water required to saturate a vessel of volume 82 L at 300 K given that the vapor pressure of water is 38 torr at 300 K.
The ...
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0answers
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Chemically generating a high vacuum?
Suppose I fill a vacuum chamber with 99% oxygen, then pull a vacuum on it down to 10 pascal absolute. If I then vaporize aluminum (for vapor deposition), will the aluminum bind with the remaining ...
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2answers
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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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1answer
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What is the temperature of evaporating water (not boiling)?
The vapor pressure of water at $\pu{70 ^\circ C}$ is $\pu{233.7torr}$.
If I were to put a temperature probe directly above the liquid water, what would it read?
In other words, does a water molecule ...
