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Homework Help: Determine ΔS when mixing

  1. Dec 11, 2011 #1
    1. The problem statement, all variables and given/known data

    For both H20 and D20:
    Cp = 75.5 J/mole-k for the liquid Cp = 37.8 J/mole-k for the solid ΔHfus=6.01 kJ/mole.

    Liquid H20 and D20 form an ideal solution.

    a) One mole of liquid H20 at 10 C is mixed with four moles of LIQUID D20 at 0 C in an insulated container.
    Determine ΔS.

    b) One mole of liquid H20 at 10 C is mixed with four moles of SOLID D20 at 0 C in an insulated container.
    Determine ΔS.


    2. Relevant equations

    ΔSmixing = -R(nX1lnX1 + nX2lnX2)

    3. The attempt at a solution

    I found
    ΔSmixing = -R(nX1lnX1 + nX2lnX2) = -8.324[(1mol)(1/5)ln(1/5) + (4mol)(4/5)ln(4/5)] = 8.612 j/mol-k

    I don't really understand the question. Can someone explain some of he concepts I need to know or direct me to somewhere where it sums it up?

    What are the steps to solving this? What do I have to think about? (Like...I know X, so I get Y because of Z)
     
  2. jcsd
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