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Does electronegativity affect rate of entropy increase?

  1. Apr 13, 2015 #1
    Let's say we have two samples of pure Helium-4, and two other samples of pure hydrogen fluoride (consisting of Hydrogen-1 and Fluorine-19) all in separate containers. One container of each chemical is at the same initial temperature of 200°C at a pressure of 101kPa, and the other ones are at 500°C and at the same pressure (i.e. one Helium container at 200 degrees and the other helium container at 500 degrees, and the same thing for HF). Because of the difference between the electronegative values of hydrogen and fluorine, the H-F bond will be highly polarized, whereas the monoatomic He atoms will just have temporary dipole induced forces of attraction. Now let's say that the two containers of the corresponding chemicals are then linked together. Clearly, there is no equilibrium now (transfer of heat is possible because of temperature differences), and assuming that the containers which are joined together are completely isolated from their surroundings, each chemical system will evolve towards thermodynamic equilibrium. My main question is, will the difference in electronegative values which induce forces of attraction of different strengths among the particles affect the rate of increase of entropy of an isolated system? Will the Helium-Helium mixture reach maximum entropy (or rather tend to it) faster than the HF - HF mixture? If I used chlorine-35 instead of Helium-4, what difference would it make?

    I'd prefer a stand alone qualitative description along with a separate mathematical treatment, if possible. Thanks for reading!
     
  2. jcsd
  3. Apr 14, 2015 #2

    mfb

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    Staff: Mentor

    Convection will dominate the heat transfer if the system is not too small, but that should be very similar for both gases.
    The helium atoms are lighter and therefore faster, which should speed up heat transfer.
    HF has a larger heat capacitance as it has more degrees of freedom than the single helium atoms, so more energy has to be transferred which should slow down the process for HF.

    Details of the collisions of the molecules/atoms might be relevant at higher orders, but there are massive differences that are irrelevant of electronegativity.
     
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