# Questions tagged [evaporation]

The process of a liquid changing to a gaseous state

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### Why should the rate of evaporation of liquids depend upon the rate at which the gas molecules strike the surface?

This paper says: The development of the kinetic theory of gases led to the conclusion that the maximum rate at a particular temperature would be given by the rate at which molecules strike the ...
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### Energy Benefits of Using Windows Vacuums to Remove Water That Otherwise Evaporates and Absorbs Energy

I've been using a new window vac and pondering its effect on the temperature in the house - and there seems nothing written about this that I can find. Plainly when the water evaporates energy is ...
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1 vote
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### During evaporation, why would we expect temperature of the gas at the interface to be lower than the temperature of the liquid?

This paper says that, from the kinetic theory of gases, we expect temperature of the gas at the interface to be lower than the temperature of the liquid. Could the experts here please explain it? ...
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### Is there any study of the temperature gradient at the surface of a liquid?

My tiny brain expects liquids to be cooler at the surface due to evaporation. However, I couldn't find any experimental evidence for it. Is there any study of the temperature gradient at the surface ...
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### What is the mechanism of sublimation?

Evaporation can be easily understood from the Maxwell-Boltzamann distribution. There is always a finite number of high speed atoms/molecules, however small, which have the energy to leave. Solids do ...
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### Center of mass thought experiment

Suppose we have a cylindrical container which contains water filled up to the brim. We now consider gravity free conditions. Then we shine some light on the water container from all the directions (...
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### Drying polymers (e.g. FDM 3D printing filaments)

As far as I understand, a polymer absorb some moisture and amount of (maximum) moisture that can be absorbed depends on its type (PLA ~1%, ABS? ~10%). Both simple commercial filament dryers and drying ...
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### Earthen Pots made in summers vs winters

I've heard my parents saying that the water in earthen pots that are made in winters cools more than a pots that are made in summers. Is this true according to physics? I understand the process of ...
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### How to obtain this expression of the Reynolds number for evaporating falling films?

The Reynolds number for evaporating falling films on a vertical plate is expressed as $$\mathrm{Re}=\frac{4\Gamma}{\mu}$$ but what are the steps that would take me from the common formula for the ...
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### How to dry a cup?

If you wash a cup and shake it out thoroughly so there are no longer any drops of water large enough to move, it seems like the cup ought to dry faster by putting it right side up, since all drying ...
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### Flux pinning upon a ultracold vapor of neutral atoms

Suppose I have a mixture of two different atoms A and B, both with an even but different number of electrons which fully fill both of their outermost shells. The two are different elements. Now, ...
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### Why do coloured water droplets form rings upon drying up?

While cleaning my fountain pen, I spilled some water on the table. The water drops had some ink dissolved in them. When these drops dried up, the deposited pigment density was visibly much higher near ...
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1 vote
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### What's the percentage/relationship of evaporative cooling applied to the liquid by an evaporating/expanding gas?

The example below is simply to provide illustration of the problem. This isn't a homework question. I'm trying to visualize the relationship between liquid and gas at the boundary and I'd appreciate ...
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### Why aren't positive ions emitted at the same rate as electrons via thermionic emission?

The Effective Work Functions of the Elements are very similar for removing an electron or a positive ion, e.g. about 4.5 eV for Tungsten. If their work functions are similar, why aren't positive ions ...
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1 vote
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### Water Vapour and Liquid Water Interactions

It is known that a certain number of particles in a sample of water have enough kinetic energy to ‘escape’ from their intermolecular bonds and into the gas phase. But what is stopping these water ...
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### Temperature and correlation with evaporation [closed]

If as water evaporates it carries energy with it and therefore there is a reduction in temperature, why does the temperature remain constant in the phase transition between liquid water and gas water?...
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### Vaporization at constant volume

my question is the following: how much energy does it take to evaporate a liquid at constant volume? For constant pressure, it’s very easy: Q = ΔHvap (Q in J/mol). However, the enthalpy of ...
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### Is it possible to cool a hot drink by inhaling the steam from the drink?

Say we have a hot cup of coffee that is giving off steam. It is releasing heat into the environment through radiation and conduction. The steam is from certain particles reaching a high enough kinetic ...
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1 vote
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### Is it possible for an absorption refrigerator to pump heat to a reservoir that is at a higher temperature than the heat source used to run it?

Judging by the wiki page I get the feeling that this type of heat pump would not function if it's radiator were hotter than the heat source, but I can't quite put into words why and I feel like there ...
1 vote
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### Why does the boiling water in the pot get sucked up by the jar?

In order for the jars to be sterilized for pickling tomatoes, they need to be boiled. But when one of the inverted jars was standing on the rack in the pot, it started sucking in the water that was ...
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### Why does blowing air on wet bodies dry it? [duplicate]

Suppose I blow dry a region with some water on it. Would it dry it faster than otherwise? If yes, why? I can give one qualitative reason against it, since the blow dryer is blowing room temperature ...
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### Why is vapor pressure well-defined?

(I am self-studying as can be verified from my post history and, additionally, I believe this question has more general applicability.) Callen asks us to consider the following in his famous textbook: ...
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### Evaporation when the air is colder than the liquid water

I am currently thinking through evaporation over lakes, specifically the Laurentian Great Lakes (a complex subject, I know). Particularly, I am trying to wrap my head around why evaporation peaks in ...
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### How does evaopration and diffusion affect concentration of solute at the solvent surface?

Imagine a long, thin tube with one end sealed and the other end open. It is filled with a volatile solvent with a dissolved non-volatile solute. As the solvent evaporates at the liquid surface, the ...
379 views

### How to understand this derivation of Raoult's Law?

A derivation of Raoult's Law in a textbook is as follows: I cannot follow the chain of arguments: Why should $p_{A0}=p_{B0}$ ? A and B are basically two different substances, each of which has a ...
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### What is the physical reason for why hot air holds more water vapour, and how does this relate to saturation vapour pressure?

It is said that hot air holds more water vapour. I guess this means that the saturation vapour pressure of water in air increases with temperature. Is this correct? How can one derive this result? ...
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### How does the drying of dishes outdoors by a cool wind on an overcast day relate to heat?

On a hot summer day, dishes dry outdoors almost immediately. At other times, a cool wind with an overcast sky will sometimes also dry dishes outdoors after a while. I am aware that some heat still ...
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### What happens in a steam convection oven at 350 F?

Assume you have an oven chamber of fixed volume (let's say $1 \text{ m}^{3}$) which also releases any excess pressure. At the bottom is a tray that contains boiling water. You heat up the oven until ...
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### Why water or condensation in a narrow neck open bottle can't seem to evaporate completely?

When I clean a soda bottle with water, empty the water out and leave the bottle open for days and the inside wall of the bottle seems to stay "wet" not "dry"?
1 vote
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### Vapor Pressure and Equilibrium

I am still fairly new to physics, and my questions might come foolish to the more professional; but these are honest questions that I feel restrained in understanding. I believe I partially got the ...
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### Derivation of the Antoine equation

The vapour pressure $P^0$ of a pure substance can be approximated by a semi-empirical formula called the Antoine equation, which says $P^0$ is related to the temperature $T$:  \ln(P^0) = A - \frac{B}...
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### How has Earth's atmospheric water been in previous eras and periods?

How has partial pressure and net amount of water vapor and colloidal water been in previous eras and periods on Earth?
1 vote
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### Why does a small puddle of water evaporate faster at the edges than the center?

I have read that ceiling tile stains and coffee ring stains are darker on the edges than the center because the puddles evaporate fastest at the point of contact between the surface, air, and water ...
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1 vote
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### I’m trying to humidify my house by evaporating water in a vessel on my wood stove. Will a lidded teakettle produce more or less vapor then a open pot? [closed]

I found a tea kettle that looks very nice on our wood stove but am thinking that using an open pot would be more efficient at humidifying the air due to the larger exposed surface of the water vs ...
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### Gas expansion during phase change (intense boiling) relation to liquid level rasing to overboiling level of a container (Literature?)

I'm looking into the area of "slugging" in open-containers which are containing a pure substance undergoing a phase-change from liquid->Vapor. I'm trying to find a connection between ...
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### Disappearing cola in a hot car

I unadvisably left an unopened can of cola in my car on a very hot, sunny day. The top blew off and when i recovered the can it was clean and dry inside. Except for a few sticky droplets on the ...
1 vote
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### Why doesn't the number of $\rm H_2O$ molecules evaporated depend on the number of the other gaseous molecules?

I have a conceptual contradiction. Say we remove a partition between liquid water and gaseous nitrogen at constant volume and temperature. The average number of gaseous water molecules will increase ...
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### Maximizing the smell of coffee in the morning

I bring coffee in a partially filled thermos. The hot coffee evaporates a bit into the cushion of air between the coffee and the lid, the air + coffee vapor mix heats up by heat exchange with the ...
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### Air temperature drop by water mist cooling [closed]

if we have a volume of air (1m3/1'200g) at a certain temp (25°c) and let water evaporate into it, what is the max achievable air temp drop? how much water has evaporated (i guess i can calculate the ...
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### Evaporation time for a Mercury-Ball

How long does it take for a Mercury-Sphere to evaporate, if it has a diameter of 1mm and the temperature is 25 Degrees Celsius and the air moves at a speed of 1km/h over it? What would the formula for ...
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### Amount of water vaporized when cooled down naturally

Suppose we have $m_i$ kg of liquid water at $100 °C$. This water cools down to $20 °C$. We want to estimate roughly the amount of water that would have to evaporate, in adiabatic conditions with the ...
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### Could a window mounted wet cloth sheet chill a room?

Assuming there is a light wind, that construction is partly shaded and a constant water pouring and evaporation of the material is occurring due to the breeze.
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### Why do clouds have well-defined boundaries?

Why do cumulus clouds have well defined boundaries? In other words, what are the physical mechanisms that hold a cloud together, as an entity separate from other clouds, that prevent it from spreading,...
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### Most efficient method to evaporate a metal in a vacuum?

If one had a metal block (lets say tantalum) in a vacuum chamber, what would be the most efficient way of evaporating it in regards to the proportion of the input energy directly going into removing ...
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### If gravity was lower but air density was the same, how would evaporation be affected?

I'm confused about the relationship between air density, air pressure and gravity. Does water evaporate faster under low air pressure simply due to the air density being lower? If the air pressure was ...
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### Does gas pressure impact the rate of evaporation?

As we know, evaporation occurs when a liquid molecule has a kinetic energy that is greater than the minimum amount of energy needed to overcome the intermolecular attractive forces holding it in the ...
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### Why water vapor condenses on glass? [closed]

I've read an answer to this question that stated glass was colder than air, causing this transfer of energy from the vapor to the glass, creating this condensation. But why is the glass colder than ...
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### Why do we feel cool after switching fan? [duplicate]

Please see that my actual question is not similar to this: Why do we feel cool when we turn our fans on? Suppose I switched my fan on. The air particles start moving. Since, their kinetic energy ...
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### Can oil "boil" in vacuum ? (Is it usable to make absolute (low) pressure measurement ?)

In order to measure vacuum absolute pressure, I thought about making a water column barometer, however, water will boil under high vacuum. Can I use oil instead ? On one side, I would expect any ...
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