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Homework Help: About matter

  1. Aug 25, 2010 #1
    about "matter"

    1. The problem statement, all variables and given/known data
    1. The forces between molecules in a substance are primarily
    a. electrical
    b. gravitational
    c. chemical
    d. mechanical

    2. If a substance is heated
    a. the molecules lose potential energy
    b. the molecules lose kinetic energy
    c. the temperature determines the quantity of internal energy
    d. the internal energy of the substance is increased

    3. Which one is right if the liquid is mercury
    a. 109.jpg
    b. http://wikipremed.com/image_science_archive_th/010108_th/117850_256px-CapillaryAction.svg_68.jpg (only observe first two tubes from right)

    2. Relevant equations

    3. The attempt at a solution
    1. answer : a
    reason : not sure, just read it somewhere and don't know why. Can someone please explain it why?

    2. between (a) and (d), but I chose (d).
    reason : if the substance is heated, it will absorbs heat energy and internal energy increases?

    3. the difference between first and second picture is the height of mercury. In picture (a), the smaller the tube, the mercury will rise closer to to the surface. In picture (b), the smaller the tube (the right-most tube), the mercury will drop further from the surface.
    My answer : second picture is correct because the smaller the tube, cohesion will be bigger and mercury molecules will attract each other more and cause the it to drop further.

    Please help me. Thank you very much
  2. jcsd
  3. Aug 27, 2010 #2
    Re: about "matter"

    please help me
  4. Aug 28, 2010 #3


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    Gold Member

    Re: about "matter"

    It's so badly worded. All chemical bonds/intermolecular forces are electrical. It's common to say that solids are held together by electrostatic forces in the sense that electrons are shared across atoms. (Think covalent, ionic, metallic.)

    Those forces aren't what is asked for though, because they say "between molecules". The intermolecular forces arise from electric dipoles rather than sharing of electrons. So someone could call them "chemical forces" if they wanted to. Just be prepared to argue either way.
  5. Aug 28, 2010 #4
    Re: about "matter"

    OK, I think I get what you mean. Can you please help me on other questions?

    Thank you very much
  6. Aug 28, 2010 #5


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    Gold Member

    Re: about "matter"

    But you already answered the other questions! Have some confidence.
  7. Aug 28, 2010 #6
    Re: about "matter"

    I am not sure if my answer is right so I asked for confirmation. But I think my answers are correct.

    Thank you very much for your help
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