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State of matter?

  1. Feb 7, 2005 #1
    How do you know if something is a solid, liquid or gas. Like ferrous iodide or sodium phosphate?
     
  2. jcsd
  3. Feb 7, 2005 #2

    chroot

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    As far as I know, there is no way to tell just by looking at the chemical formula.

    - Warren
     
  4. Feb 7, 2005 #3

    chem_tr

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    Physical state may change upon temperature, pressure and even time...
     
  5. Feb 7, 2005 #4

    dextercioby

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    Could you please give an example of a phase trasition of the first kind in which,assuming a system in one phase (e.g.solid) and nonmodifying the external conditions (temperature,pressure and other parameters),the system would undergo a phase transition (into e.g.fluid)??

    Daniel.
     
  6. Feb 7, 2005 #5
    Well,...you can sorta guess as to which "state" a compound is by looking at what bonds it together;

    For example, MgBr2 is probably a solid because of the ionic bonds;
    Li2 is a solid by metallic bonds
    O2 is a gas, because its covalent bond is very weak
    CH3COH may be liquid, because of the dipole-dipole intermolecular attraction with that OH end there

    Network compounds are usually solid, as they possess very strong covalent bonding, so are ionic compounds, because ionic bonds are strong as well

    H2 is a gas, because it has almost no intermolecular force between the H2 molecules

    Well, given the formula, you can generally "sorta" guess as to what its state would be at STP--to verify this and to check for other temperatures/pressure, see a phase diagram for your compound
     
  7. Feb 7, 2005 #6

    Gokul43201

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    I think chem_tr may be refering to non-equilibrium (metastable) states.
     
  8. Feb 7, 2005 #7

    dextercioby

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    It's the only reasonable explanation...

    Daniel.
     
  9. Feb 8, 2005 #8

    chem_tr

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    Yes, I meant metastable states; Gokul is right.
     
  10. Nov 18, 2009 #9
    Milk. Milk turns into powder over time.

    Although, I'm not sure, as technically milk is composed of a lot of elements, you may be looking for a compound or singular element, not just a mixture.
     
    Last edited: Nov 18, 2009
  11. Nov 19, 2009 #10

    alxm

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    'Metastable' can be a bit misleading though. Diamonds are pretty stable at STP.
     
  12. Nov 19, 2009 #11

    alxm

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    That's evaporation, not a phrase transition.
     
  13. Nov 19, 2009 #12

    Borek

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    That's necromancy, last post in the thread was almost 5 years old.
     
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