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Questions tagged [evaporation]

The process of a liquid changing to a gaseous state

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Can we enhance evaporation rate with a vacuum pump?

First, consider having water at 100C and 1atm and a heat source. If more heat added to water, we have more evaporation rate according to the following formula: $$Q_{in}=m_{vapor}*h_{fg}$$ THEN ...
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Water at 0 atmospheric pressure

Suppose I put a bucket of water on the surface of the Earth. Then somehow the atmosphere disappears. My question is: Would the water fly out of the bucket, or would it be still there? My reasoning ...
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Amount of Steam Generated using Gas burner and Induction cooker

I did an experiment, by boiling water using two different heat source. At first, i boiled water using a gas stove then i repeat by using an induction cooker. I noticed that the amount of steam (...
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Effect of pressure when drying wet clothes in a windy environment

When we hang wet clothes outside, they dry faster if it is windy. The wind causes forced convection and removes the air saturated with vapor, and the rate of evaporation does not decrease much in ...
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Why perspiration drops are seen in shopping bag?

Why perspiration drops are seen in shopping bag? When i put hot bread in shopping bag after sometime i saw perspiration drops in the shopping bag.
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Will having two water pans in my smoker make any difference?

I have a backyard smoker, and I use a tray of water in it as thermal mass to help keep the temperature stable. I don't think the size of the tray is going to matter, but it's roughly 40cm x 30cm x ...
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Potential Energy of Particles

I read the following statement in my textbook While a liquid is boiling, the energy supplied to the liquid goes to breaking the bonds between neighbouring molecules. Can anyone explain the process ...
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What happens at the molecular level during evaporation?

During boiling the liquid gets its energy from the heat source so it can break the force between molecules and turn into gas while evaporation happens at the top of the liquid at any temperature. ...
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Does the presence of a flame affect the flow rate of gas out of a lighter or torch?

If I were to set a propane torch's valve to a fixed open position, would it run out of gas faster lit or unlit? Does the flame produce any kind of pressure change that affects the flow rate through ...
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Evaporation amount of water for a Storm [closed]

How much water from the ocean is evaporated for a storm over water? I am trying to figure out what conditions will cause the most evaporation or how to calculate the amount of water evaporated for a ...
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Can a substance have zero vapour pressure above absolute zero?

According to this Reddit thread, the answer is no, vapor pressure can't be zero when temperature is above absolute zero. I suspect the answer might actually be yes according to a precise definition I ...
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Will water in a vacuum evaporate continously?

Will a vacuum chamber that is maintained at 0.1 Atmospheres with an open water container inside ever reach 100% humidity of the remaining air, so that no more water evaporates or will water ...
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Simple question about molecules leaving a liquid at a temperature below the boiling point

My textbook asks the question why a liquid cools down when partial evaporation occurs just below the surface at a temperature below the boiling point. The answer is of course that only those ...
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Is it possible to force a temperature difference using evaporation/condensation cycle?

Here's a picture of my supposed "cooler": The apparatus has following properties: The bottom and upper part: thermally very conductive Side: thermally very non-conductive The "some liquid" is an ...
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Temperature Proxy (Climate)

At the bottom of the wikipedia article on climate proxies there is this formula: $$ \delta \, {\rm ^{18}O} = \frac{\frac{\left[\rm{^{18}O}\right]}{\left[\rm{^{16}O}\right]}}{\frac{\left[\rm{^{18}O}\...
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Calculating gas pressure following water transformation to vapor (in contact with boiling oil)

When water falls into a pot of boiling oil, it turns into vapor, and in an enclosed space this will create a higher gas pressure. Is there a way to figure out how high of a gas pressure there will be ...
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What type of heat is efficient to evaporate water?

I found that there are several type of heating element in a hair dryer, but basically I mainly classify them into two ways of heat transfer: Radiation and Conduction. The conventional hair dryer uses ...
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Why does evaporation cause cooling?

I am aware that the evaporation process causes cooling in the remaining liquid, but why? If anyone can give me the maths and or equations to prove / show this I would be most appreciative.
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Do solids do something analogous to liquids evaporating below their boiling point?

I'm probably not entirely right, but evaporation differs from boiling in that it is surface rather than bulk phenomenon driven by a pressure gradient rather than temperature. If a volume of liquid is ...
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Evaporative calculation

I have some questions on evaporative calculation. That is, if I have a solution at temperature A initially, and it was placed at an environment of temperature A as well. Due to evaporation, the ...
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Why do really cold objects evaporate really quick? [closed]

So I saw a video of LNG (liquid natural gas) and when it got in contact with water, which was room temp the LNG evaporated instantly...why? Ice takes a while to evaporate like a sec even when hot ...
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Rate of evaporation/mass loss of liquid in a bowl

Say a hemispherical bowl filled with a liquid was left in a room. I was wondering how we could model the rate of mass loss of liquid as it evaporates. Will it be a quadratic relationship with time? ...
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Does the saturated vapor pressure depend on the external pressure or just only temperature?

So far I understand that the saturated vapor pressure is the pressure exerted by a substance in liquid (or solid) vapor equilibrium, and that this pressure depends on the temperature of the system. ...
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Evaporation inside a container

This is for my engineering design project and our group needs to make a storage where humidity inside should be maintained above a certain range. So as a simple prototype, we simply added a bit of ...
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Can a droplet of formalin evaporate in midair while falling? [closed]

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 ...
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Interesting thought experiment on evaporation and pressure

Little background: the enthalpy of vaporization equals energy required to change state, plus the work done against ambient pressure. Say I made a balloon with Gore tex.(Gore tex is a fabric that ...
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Why are the wet patches on these floor tiles circular?

My friend's 3-year-old daughter asked "Why are there circles there?" It had either rained the night before or frost had thawed. What explains the circles? Follow-up question: Ideally, are these ...
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How can frozen clothes dry overnight?

I put some wet Polyester clothes outside for the night (the clothes were washed by hand with pretty cold water -maybe around 4°C- and wringed by hand so there was still water dropping of them when I ...
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Is it possible to explain evaporation using thermodynamics only?

I'm wondering whether it's possible to explain water evaporation using the theory of thermodynamics only, as opposed to the commonly cited statistical mechanics. Indeed, the usually given explanation ...
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How to calculate vaporization energy of water given a defined surface and liquid temperature?

One Stainless Steel container with inner diameter of 300mm Open system Ambient temperature 25 Celsius Water temperature is Regulated to 90 Celsius Assuming that we neglect energy lost by ...
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Why does water droplet change shape as it evaporates?

This .gif was posted on reddit /r/gifs, with title "A water droplet evaporating." I'm not actually sure if that is actually the case here. Regardless, if we were to look at the process we can see ...
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Are there materials with a negative enthalpy of vaporization?

I just answered a question about boiling water which concerned the vaporization enthalpy of water — the energy needed to evaporate it, ceteris paribus —, which is substantial. I was ...
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How do we compare the effect of air pressure and the effect of temperature, on evaporation?

Let's say we have some water with a boiling point of 90 Celcius in it's current environment; and with the same mass, same humidity, same bucket and all, we have some water with a boiling point of 100 ...
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Can I increase cooling efficiency with evaporative cooling?

I had an idea recently. But I don't have the physics knowledge to know if it makes sense or not. I've become a bit of a PC enthusiast lately and one thing that is big in the PC world lately is water ...
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Why don't liquids just boil off in the open just as they would in a vacuum?

I understand that all solids and liquids are unstable to vaporisation in vacuum (because some molecules will always have the energy to escape the bonds due to the nature of thermal energy distribution)...
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Purpose of coil in liquid propane torch

Many liquid propane torches (including burners for hot-air balloons) have coils placed in the line of fire heating the liquid before it reaches the nozzle. I am very puzzled by the exact function of ...
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What law or formula discusses the relationship between pressure and dew point?

A lot of times, dew point is focused primarily upon temperature and relative humidity. However, that same point of saturation is affected by the pressure, but I can't find a formula, or law even, that ...
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Is vapor pressure affected by dissolved gasses in the liquid?

If I take a half full bottle of water, seal it with a pressure gauge, and wait a few days then it will be at equilibrium. If I observe the pressure, that would be the water vapor's pressure. However, ...
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If I boil water at room temp using a vacuum, will the water instantly liquify if I reintroduce air to the system?

If I boil water at room temperature in a vessel using a vacuum pump, will the water instantly liquefy and fall back into a liquid pool if I reintroduce air into the system? Basically, if this is a ...
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Must gaseous water be 100C (or greater) regardless of pressure?

I know that if you evaporate a molecule of water, that it must be 100C in order to be gaseous, so that it will take that heat with it if it wasn't already that temperature. This has a cooling effect ...
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Is water vapor in a metastable state at 1 atm and at room temperature?

At 1 atm and room temperature, is water vapor in a metastable state? As I understand it, water vapor is water in a gaseous state when the stable phase of water under this temperature and pressure is ...
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Evaporation in Rankine cycle

I've got two questions about evaporation in Rankine cycle: Why do we first heat up to a certain temperature (a to b) and then we make it evaporate ad constant temperature (b to c)? Isn't possible to ...
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Does a glass of water at room temperature emit (infrared?) radiation

While reading the introduction to Feynman's lectures, it's mentioned how a glass of water cools down through evaporation, when some molecules get a bit extra energy and break free. If it's not a ...
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Is it possible to cover a whole lake by thermocol sheets to prevent it from evaporation? [closed]

It has been in news recently that attempts were made to cover a lake with thermocol sheets to stop it from drying. A report published by the Central Water Commission on ‘Evaporation control in ...
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Why is there bubble in the boiling water?

Whenever we boil water there, there comes bubble from the bottom surface of the kettle when the water reaches 100 degree Celsius. Why is that? We also see some bubble sticking to the surface even ...
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Why do moving water droplets form on the surface of a very hot pan? [duplicate]

https://www.youtube.com/watch?v=jrtyTN4aHmo&feature=youtu.be The above video is my recording of the phenomenon. Why does this occur at high temperatures, when at lower temperatures the water ...
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Why does drying off with a towel at room temperature not feel cold?

I thought that if you're wet, a breeze will feel cold because the water moisture is evaporating and whisking away heat along with it. With a towel at room temperature (same temperature as a breeze), ...
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Evaporation occurring throughout

Do liquid and gaseous molecules coexist below the surface of a pure substance at temperatures below the liquid's boiling point temperature?
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Why does temperature remain constant at the boiling point of the liquid? And what kind of an equilibrium is boiling?

When we were in school, the teachers used to tell us that heat increases the kinetic energy of the particles (reflected in the temperature) until the boiling point is reached. Afterwards, all the heat ...
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Where is latent heat picked from?

I wash my clothes, remove it from the washer and put it on a dryer rack. Then, water contained in the wet clothes naturally evaporates and becomes dry overtime. I understood this occurs from latent ...