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Thread: Question about boiling point of water

  1. #1 Question about boiling point of water 
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    The boiling point for water is 100C. So why at room temperature does water evaporate. If you take a shower, your hair drys at room temperature, and if you add certain things like a fan blowing in your hair it will evaporate even faster, why is this?

    Is it because water evaporating is an endothermic process and everytime water evaporates the remaining liquid has less energy to allow more water to evaporate?


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  3. #2  
    Forum Ph.D. Cat1981(England)'s Avatar
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    Water molecules don't normally have enough energy to escape the surrounding liquid. When the molecules in the liquid collide, sometimes they transfer enough energy to a particular molecule near the surface to allow it to escape the liquid. This process happens millions of time a second and is called evaporation. Boiling is a different process.


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  4. #3  
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    Quote Originally Posted by Cat1981(England)
    Water molecules don't normally have enough energy to escape the surrounding liquid. When the molecules in the liquid collide, sometimes they transfer enough energy to a particular molecule near the surface to allow it to escape the liquid. This process happens millions of time a second and is called evaporation. Boiling is a different process.
    How is boiling different than evaporation? In both processes water goes from a liquid to a gas, just with evaporation it takes longer, what else?
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  5. #4  
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    Quote Originally Posted by Raymond K
    Quote Originally Posted by Cat1981(England)
    Water molecules don't normally have enough energy to escape the surrounding liquid. When the molecules in the liquid collide, sometimes they transfer enough energy to a particular molecule near the surface to allow it to escape the liquid. This process happens millions of time a second and is called evaporation. Boiling is a different process.
    How is boiling different than evaporation? In both processes water goes from a liquid to a gas, just with evaporation it takes longer, what else?
    When water evaporates, only the molecules in the surface can turn into gas. In boiling process water goes from liquid to gas everywhere. That's why you see bubbles coming up in the boiling water.
    So the difference is where the gasification happens.
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  6. #5  
    Forum Ph.D. Cat1981(England)'s Avatar
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    Just to add to what Elina has written, both evaporation and boiling are forms of vaporisation, however, boiling is a form of phase transition such as freezing or melting and can occur anywhere in a body of liquid were the temperature is above the materials critical temperature. Evaporation can only occur below the critical temperature and only on the surface of the body of liquid. Evaporation can also occur in some solids such as ice, we call this sublimation though.
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  7. #6  
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    Elina, Cat1981, you seem to know what you're talking about.

    Do me a favour by looking into this thread ?
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  8. #7 Water. 
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    Water also boils faster if its under preasure.

    What happens to water if its inside a sphere, and no possibility for it to escape as vapor. Lets asume we have a sphere that can hold infinite preasure. Will the electrons in there just go crazy? Will it change into something else?

    Purely philisophical atempt.

    Im sorry, if i should have made a new tread in the philosophy section on the board.

    Ok,,i made the tread. We can now, debate it from this tread in philosophy.
    http://www.thescienceforum.com/viewt...=13752&start=0
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  9. #8 Re: Water. 
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    Quote Originally Posted by Thermaltake
    Water also boils faster if its under preasure.
    No, it wonít. A higher pressure raises the boiling point of water.
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  10. #9 Re: Water. 
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    Quote Originally Posted by JaneBennet
    Quote Originally Posted by Thermaltake
    Water also boils faster if its under preasure.
    No, it wonít. A higher pressure raises the boiling point of water.
    Yes my misstake.
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  11. #10 Re: Question about boiling point of water 
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    Quote Originally Posted by Raymond K
    The boiling point for water is 100C. So why at room temperature does water evaporate. If you take a shower, your hair drys at room temperature, and if you add certain things like a fan blowing in your hair it will evaporate even faster, why is this?

    Is it because water evaporating is an endothermic process and everytime water evaporates the remaining liquid has less energy to allow more water to evaporate?
    Hello,

    a very good question I got no answer on.

    might be the boiling point, boiling water, can not be mistaken with the actual evaporation process on the one hand, or, water was, somehow, heated to evaporate, if it does, partially on the other. By a an energy source like the sun for example. Water as prism maybe?

    Steve
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  12. #11  
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    Change the word boiling point to turning point. This can explain everything. That is a point from liquid state to gas. Water canít stay in liquid state above the point.
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  13. #12  
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    Haha.... what does it explain? And how?

    Steve
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