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Thread: Matter

  1. #1 Matter 
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    Matter is defined as anything that has mass and occupies space. This made me curious to know if there was anything that had mass, but did not occupy space or occupied space but didn't have mass.

    Edit: I thought of another question while sitting here reading my textbook. If the difference between a gas and a liquid is the molecules in a gas are far apart and in a liquid they are closer together, when a gas is compressed, what keeps the gas from becoming a liquid?


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  3. #2 Re: Matter 
    Reptile Dysfunction drowsy turtle's Avatar
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    Quote Originally Posted by JMC838
    I thought of another question while sitting here reading my textbook. If the difference between a gas and a liquid is the molecules in a gas are far apart and in a liquid they are closer together, when a gas is compressed, what keeps the gas from becoming a liquid?
    If compressed under sufficient pressure, it will turn into a liquid. At moderately high pressures, the kinetic energy of the molecules is so great that the intermolecular forces that characterise a liquid never really form, so although the molecules are packed close together, the crucial difference is there would be no internal forces holding them together.


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  4. #3 Re: Matter 
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    Quote Originally Posted by JMC838
    Matter is defined as anything that has mass and occupies space. This made me curious to know if there was anything that had mass, but did not occupy space or occupied space but didn't have mass.
    I believe the electron has mass and can be described it as a point-like, dimensionless "object" which does not occupy space.
    At other times this description appears to be considered as a convenient, useful, fiction and the electron is thought of as having wave-like properties.
    I am sure there are others posting, on the forum, who have a deeper knowledge of such questions.
    I say that because I think it is only possible to "describe" or properly understand objects, such as the electron, mathematically.
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  5. #4 Re: Matter 
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    Quote Originally Posted by drowsy turtle
    If compressed under sufficient pressure, it will turn into a liquid. At moderately high pressures, the kinetic energy of the molecules is so great that the intermolecular forces that characterise a liquid never really form, so although the molecules are packed close together, the crucial difference is there would be no internal forces holding them together.
    That makes sense. Thanks for the response.
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  6. #5  
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    This discussion is leading quite nicely onto the dynamic area of supercitical fluids. As drowsy turtle wrote, a gas sufficiently compressed will adopt liquid characteristics, However the same compression at elevated temperatures will promote exhibition of liquid and gas-like properties similtaneously. These materials have found very interesting uses in chemistry throughout recent years, such as CO2 used to extract caffene from coffee.

    By looking at experimentally derrived phase diagrams, such as

    http://www.teachersparadise.com/ency...phase_diag.png

    you'll see that temperature and pressure can be used to convert matter between states, however at the extreems of temperature and pressure, ie the critical point, the materials become something quite exciting indeed!
    Chemistry is everything!
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