What happen to the kinetic and potential energy during the boiling and melting?

  1. I know this question is probably chicken feet to most of the people here, and I hope I am posting on the right thread. But I am just curious about 2 questions;

    1 - Where does the kinetic and potential energy comes from in a substance?
    2 - How are the kinetic and potential energy affected by boiling or melting?

    Any reply would be a real help. Thanks =D
     
  2. jcsd
  3. Substances are composed of atoms or molecules. They are in constant motion (vibrating or translating depending on the state of the substance).
    Temperature is the average kinetic energy of a molecule of that substance.
    There are connections between the molecules (chemical connections) - potential energy of the substance.
    The whole energy of all the molecules (kinetic and potential) is the internal energy of the substance.
    If you place another substance(2) in contact with the substance(1) the molecules of the two substances will come in contact and will tend to even their kinetic energies (temperatures).
    Heat is the energy that has been transfered.
    When a substance goes from one state to another the addition of heat does not increase the temperature of the substance but is used to brake the connections between molecules (to bring the molecules to higher potential level).

    From this I hope you can answer those questions.
     
  4. So basically, while the change of state is occurring only the amount of potential is changed while kinetic energy remains the same? Thanks a lot. That was really helpful.
     
  5. Yes, that energy is called latent heat (heat of transformation).
    I'm glad I was able to help.
     
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