Evaporation 3220
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Evaporation is the name given to the process in which a liquid is converted to the gaseous state. Everyone is familiar with the process of evaporation. Suppose that you spill a teaspoon of water on the kitchen table. If you come back a few hours later, the water will have disappeared. It has changed from liquid water into water vapor, or evaporated.

Molecular explanation

Evaporation occurs because all molecules of all substances are constantly in motion. Consider the molecules that make up a teaspoon of water, for example. Those molecules are constantly in motion, flying back and forth within the water, sometimes colliding with each other. When collisions occur, some molecules gain energy from other molecules.

Those changes make little difference for molecules deep within the water. But for molecules at the surface of the water, the situation is different. Molecules at the surface that pick up energy from other molecules begin to travel faster. Eventually, they may be able to travel fast enough to escape from the surface of the water or to evaporate from the water.

This process continues as long as water molecules remain. Molecules that were once inside the water eventually work their way to the surface. When they pick up enough energy by colliding with other water molecules, they too escape. Eventually, no water molecules remain. The liquid has completely evaporated.

The remaining liquid

This description explains an interesting fact about an evaporating liquid: its temperature decreases as evaporation occurs. Remember that surface molecules escape from the liquid as they pick up energy from other molecules. The molecules left behind, therefore, have less energy than they had before the collisions. Since they have less energy, they also have a lower temperature.

The human body uses this principle to remain cool. On a warm day, we perspire (sweat). Sweat evaporates from the skin, taking body heat with it. As a result, the body is cooled.

Commercial applications

Evaporation is an important commercial process by which liquids are removed from solids. In many instances, a product is formed as the result of a chemical reaction that takes place in water. One way to obtain the final product is to simply allow the water to evaporate leaving the solid product behind.

[ See also Matter, states of ]

Also read article about Evaporation from Wikipedia

User Contributions:

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Oct 15, 2012 @ 10:10 am
Yes thank you so much for having this information, because i needed to get a science fair project done on evaporation and this might just have got me a passing grade or better.
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Oct 20, 2013 @ 10:10 am
i am actually also doing a science fair project on evaporation and this really helped
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Jun 30, 2014 @ 9:21 pm
Logan P
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Feb 11, 2015 @ 6:18 pm
The water also get energy from the air around it like sun gives off radiation or sun rays which also give energy to it. Or gets energy from the ground and the humans around it giving off energy or "heat".
lel boy
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May 5, 2015 @ 11:23 pm
why dont swimming pools evaporate?whydont fish tanks evaporate?
Kitty paw paw
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Aug 16, 2015 @ 1:13 pm
I hate this it should have shown the amount of water that evaporates in the soil
Bhavi bansal
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Aug 25, 2015 @ 11:11 am
It is good. Helped me alot in my note book submission. You need to add more stuff I think. About principals, motif, etc. I am not saying it was bad, it is up to the mark. But it can be improved more by better information in brief. Thanks alot by the way, it is easy and in simple language. Easy to understand!
Jonathan Littlejohn
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Dec 16, 2016 @ 12:12 pm
This article is very interesting but not to me. And um I am a 7th grade student at Oblong Grade school ! I'm in Mr. Blankenbaker's room 3 hours a day.
Billie Scott
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Apr 23, 2017 @ 4:16 pm
When water evaporates, do the hydrogen and oxygen atoms that make up water break apart.
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Oct 11, 2017 @ 1:13 pm
This page helped me so much i have to do a science fair and this had so much helpful information.

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