The process of a liquid changing to a gaseous state

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26
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4answers
73k views

How does water evaporate if it doesn't boil?

When the sun is out after a rain, I can see what appears to be steam rising off a wooden bridge nearby. I'm pretty sure this is water turning into a gas. However, I thought water had to reach 100 ...
23
votes
9answers
28k views

How can water evaporate at room temperature? [duplicate]

Boiling point of water is 100 degree Celsius. The temperature at which water in liquid form is converted into gaseous form. Then how it possible for water to evaporate at room temperature?
17
votes
1answer
904 views

Why does a water drop on a hot plate at $150^o C$ evaporate faster than on a plate at $200^o C$?

I recently read that: "A drop of water landing on a hot plate at $150^o C \:(300 F)$ evaporates in a few seconds. A drop of water landing on a hot plate at $200^o C \:(400 F)$ survives a whole ...
17
votes
2answers
443 views

Stripeless cleaning of windows

Cross post: http://chemistry.stackexchange.com/q/4377/22 Last week I was discussing with a friend how we thought the stripeless cleaning of windows is achieved when using a cleaner like Windex ...
15
votes
5answers
24k views

Does wrapping a wet paper towel around a glass bottle really speed up the cooling process?

There are claims like this one that you can improve the cooling speed of beverages when you put them wrapped in a wet paper towel inside the refrigerator/freezer. I've just tried it by myself and ...
15
votes
1answer
900 views

Why doesn't breath condense around poop of flies on the window's glass?

One day it was raining outside and I was breathing on the glass of my window. I noticed that around the spots of fly poop there is a circle where vapor does not condense. With time the circle becomes ...
8
votes
6answers
3k views

Does placing a lid on a pot affect the rate of boiling?

On the subject of cooking, someone once told me "If you have too much water in your pot after cooking a dish, just turn up the heat and let it boil without a lid for a few minutes". Now I've thought ...
8
votes
3answers
723 views

Why is there a hiss sound when water falls on a hot surface?

Why is there a hiss sound when water falls on a hot surface? I have searched a lot, asked my teachers but none of them seem to give me the logical answer to it.
7
votes
4answers
3k views

Sauna thermodynamics

Why does it get hotter (feel hotter) in a sauna when one pours water over the hot stones? Wikipedia says that the water condenses onto the skin, but the actual air humidity is so low that I doubt ...
7
votes
2answers
1k views

Does Uchimizu (watering streets in summer) help reduce temperature in an area?

It appears that in Japan, there is an old custom called Uchimizu. The name is a combination of words "road" and "water". The essence of it is moisturizing small parts of populated areas like ...
7
votes
5answers
231 views

What keeps water molecules in air from falling down?

I was thinking about evaporative cooling, how the particles in water with the most velocity fly out of the water, leaving it colder. But then I thought, how come these water molecules stay in the air ...
6
votes
3answers
15k views

How does an earthen pot keep water cool?

I understand that evaporative cooling takes place thanks to small pores contained in the pot and that allow some water to go through and evaporate. However I couldn't understand clearly whether water ...
5
votes
1answer
347 views

Can water evaporate when frozen?

If an ice cube is stored in a freezer could it evaporate given enough time? Is there a temperature below which water cannot evaporate (even just a little)?
5
votes
3answers
1k views

Does evaporation decrease entropy?

I have a container of water in thermal equilibrium (there are no temperature fluctuations inside the container). Some molecules will evaporate out of the container of water thus decreasing its ...
5
votes
2answers
169 views

If water evaporates at below 100 degrees then why not stone?

I have asked this question recently: Why does evaporation take place? and I got a satisfactory answer, that temperature is macroscopic and is the average temperature of the object. That said, why ...
5
votes
3answers
5k views

How to calculate the evaporative cooling rate needed to protect a house from forest fire

Recently in our area there has been a large forest fire and I've been looking into home defense from such things. I am not a physicist - but can do some basic math. I was wondering how I could ...
4
votes
1answer
635 views

Why can I see my breath after I pop my ears?

I have this weird but reproducible thing that I can see my breath for less than a second even in hot/humid weather. The key to do that is to pop my ears - I have to do that often, it's like I'm on a ...
4
votes
3answers
387 views

atmospheric phenomenon? What causes condensation trails to converge?

This air plane just caught my eye. Two contrails apparently are flowing backward, slightly off-centered and then ultimately converge, giving the overall shape of a very narrow rhomboid parallelogram, ...
4
votes
2answers
1k views

Why does evaporation take place? [duplicate]

I was looking at at puddle when I thought that this puddle will evaporate tomorrow but then it occurred to me that the boiling temperature of water (aka to turn into gas) is $100$ degrees under 1 ...
4
votes
2answers
771 views

Acer saccharum (Sugar Maple) Sap & Freezing

This may or may not be the appropriate scientific discipline to ask this question of, but I'll give it a shot. I'll happily invite chemists to chime in as well. It's time to tap sugar maples in the ...
4
votes
1answer
293 views

How would one calculate the amount of water contained in a cloud?

So I was looking out the sky one day and I wondered how I would go about calculating how much water was contained in a cloud. I figured the following simple outline 1) We need to roughly know how big ...
4
votes
0answers
24 views

Time for which a drop stays in the leidenfrost point

Is there any way to find out the time required for a drop of given dimensions to vaporize after attaining Leidenfrost point?
3
votes
1answer
698 views

Behavior of water at temperatures above 100°C

Assuming you have container with heat insulation (something like boiler). You can store water at any temperature below 100°C. At these conditions, you can drill a hole into container and store water ...
3
votes
3answers
579 views

Why does water not evaporate in below 0 degrees?

I have learnt that, most objects still have energy in their atoms until the temperature reaches absolute zero. In other words, everything has energy around us. Now, that in mind if I go to antartica, ...
3
votes
2answers
240 views

What would make the bottom of my cocktail glass develop a fractured pattern like this?

I left out the remnants of my Long Island Iced Tea. This was a mixture of various liquors, lemon juice, Splenda, and water from the melted ice. It was left on my kitchen counter for several days: ...
3
votes
2answers
198 views

Why do some hand dryers blow hot air?

I am not sure why some hand dryers are blowing hot air and not just air at room temperature. To me, hair dryers are just a way to dry one's hands using the same principle as when we shake our hands ...
3
votes
2answers
168 views

Does the temperature of water determine how much heat will be removed from air used to evaporate it?

This is a question about evaporative cooling as used in residential evaporative cooling appliances. This type of cooling uses the heat in the ambient outside air to evaporate water and remove the heat ...
3
votes
2answers
864 views

Would a small puddle of water evaporate faster if you spread a dry towel over it?

Let's say you spill 10ml of water on the kitchen counter. It forms a small puddle that would evaporate after a while (assuming room temperature and sane humidity). Would spreading a large, dry towel ...
3
votes
1answer
250 views

Hygiene thermodynamics 2

Two kinda related questions here: Is evaporation rate and temperature difference related? There is an experiment of pouring cup of hot water out the window during winter. The water evaporates almost ...
3
votes
2answers
2k views

Why can't I evaporate water without wind, just heat? (not boiling,evaporating!) Or can I?

So here is the thing, I searched all over the internet for this but all the sources say that I need wind because the process of evaporation goes as follow: Water particles at the top layer with ...
3
votes
2answers
530 views

Reducing the evaporation of water at room temperature

Water drops kept on different surface evaporate after a few minutes. How can I reduce the rate of evaporation of these drops? Can I add some additives which suppress evaporation?
3
votes
2answers
503 views

Time to establish saturated vapour pressure above liquid

Thought experiment - a liquid is in a closed container in equilibrium with its vapour, and then suddenly all the vapour is pumped away. Switch off the pump so that instantaneosuly there is no vapour ...
3
votes
0answers
25 views

Can I always assume that a vapour pressure over a liquid is ideal?

Can I assume that the vapour of a subject over its liquid is ideal-ish? I'm thinking that if the vapour pressure is low the subject in question wont interact with itself, but it doesn't necessarily ...
2
votes
1answer
75 views

How to heat water at very high temepratures?

I am working on a project and recently came through a situation where I'll be working with water evaporation. On searching the internet I found that water heated at 350Celsius would generate almost ...
2
votes
2answers
820 views

Does coffee cool faster than tap water?

A friend of mine, based on casual observation, believes that coffee will cool faster than ordinary hot tap water. Being curious about this I have tried to investigate it myself, but I'm not well ...
2
votes
2answers
3k views

Why do liquids boil when their vapor pressure equals the ambient pressure?

Given that the boiling point of a liquid is the temperature at which the vapor pressure is equal to the ambient (surrounding) pressure, what significance does a liquid's vapor pressure have in the ...
2
votes
1answer
1k views

Can traditional steam (water vapour) exist in a vacuum?

Can steam (water vapour) exist in a vacuum, and if so does it look and behave the same as in air? Let's assume the actual case is a kettle boiling in a vacuum. Note that I'm talking about a gas-less ...
2
votes
1answer
2k views

Heat of vaporization of water - dependence on relative humidity?

Does the heat of vaporization of water depend strongly on the relative humidity of the gas into which it evaporates? Some context: If we want to calculate the dew point of water, we find the ...
2
votes
1answer
28 views

If you charge water will the evaporation rate change?

If you take away electrons or add electrons to a body of water will the evaporation rate be changed? (Even if it's brief or the effect is small)
2
votes
1answer
862 views

Calculating rate of vaporization of water

Let there be a cylindrical vessel with diameter D that only has liquid water and water vapor as the picture below shows (The water vapor is the grey portion and the liquid water is the blue portion). ...
2
votes
3answers
250 views

What limits the mass transfer from a boiler to a condenser in a sealed vessel?

If we set up an evacuated vessel where we keep one end at a higher temperature than the other, and then introduce a liquid at the warm end, it will evaporate and condense at the cooler end. If we trap ...
2
votes
0answers
507 views

How can I interpret negative values of potential evapotranspiration?

If I extract Potential Evaporation (PET, W/m$^2$) from the National Centers for Environmental Prediction (NCEP), climate reanalysis data (downloadable as netCDF files here), there are some negative ...
2
votes
0answers
123 views

Will humid air mitigate airborn dust due to neutralization of static electricity?

I have came to understand that humid air will help prevent electrostatic forces that can propel dust and cause it to cling to surfaces. My first question: is this above statement true? If the answer ...
1
vote
3answers
127 views

Why doesn't water start to boil in soils?

Consider the following two scenarios: I take a vessel filled with some water and evacuate the air, the water will (or rather can) start to boil; if the pressure in the vessel is << atmospheric ...
1
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5answers
168 views

Ice cube on a scale

Lets put an ice cube on a fairly precise scale and take readings over a period of several hours. The ice cube is situated in a saucer so that the water is retained after melting. What will the ...
1
vote
5answers
8k views

What's the surface area of a liquid? How does evaporation increase if the surface area of a liquid is increased?

Wikipedia says that a substance that has a larger surface area will evaporate faster, as there are more surface molecules that are able to escape. I think the rate of evaporation should decrease as ...
1
vote
3answers
739 views

How to accurately explain evaporative cooling?

I am trying to clearly express in one or two sentences how increased evapotranspiration could cool a region. The audience is educated but non-scientific. Is it accurate to say that the water vapor ...
1
vote
1answer
92 views

Evaporate water using compressed air [closed]

I want to evaporate water by forming air bubbles which are formed by flow of compresses air through perforations. What is the energy (in KWh) input to compress 1 cubic meter volume of atmospheric ...
1
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1answer
32 views

Pressure and Phase Experiment Questions

Consider the experiment where a test tube filled with water is inverted in a beaker of water . (The following figures are not to scale of actual apparatus.) At time t=0, the instantaneous snapshot is ...
1
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1answer
59 views

Boiling is not well described? [duplicate]

It is said that boiling occurs only when the vapour pressure becomes equal to the pressure surrounding the vapour (say atmospheric pressure). Why does it take place only satisfying these conditions ...