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Thermochemistry significance of infinitely dilute solution

  1. Dec 15, 2012 #1
    Thermochemistry significance of "infinitely dilute solution"

    1. The problem statement, all variables and given/known data
    (see attachment)


    2. Relevant equations



    3. The attempt at a solution
    I don't know where to start from and it seems to me that data given is insufficient to solve this problem. Also, what's the significance of "infinitely dilute solution"?

    Any help is appreciated!
     

    Attached Files:

  2. jcsd
  3. Dec 15, 2012 #2

    Borek

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    Re: Thermochemistry

    Infinitely diluted means all activities equal 1 (so no need for calculations of ionic strength and activity coefficients).

    Can't say I understand the question.
     
  4. Dec 15, 2012 #3

    epenguin

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    Re: Thermochemistry

    Nor me. I'm inclined to say it should be zero for infinitely dilute solutions.
     
  5. Dec 15, 2012 #4
    Re: Thermochemistry

    Is the question wrong then?
     
  6. Dec 15, 2012 #5

    epenguin

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    Re: Thermochemistry

    Is ΔFf0 defined in your text?

    Usually ΔF0 's are defined for a process not a substance, but perhaps there is a convention I am out of date about.
     
  7. Dec 15, 2012 #6
    Re: Thermochemistry

    ΔFf0? No, there is no such thing in my text.
     
  8. Dec 16, 2012 #7
    Re: Thermochemistry

    Can you tell me what does ΔFf0 mean? I will try to look it up somewhere.
     
  9. Dec 16, 2012 #8

    Borek

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    Re: Thermochemistry

    I wonder if epenguin really means ΔFf0, or did he just misread the problem. F is sometimes used for Helmholtz free energy, but I think question lists ΔHf0 - enthalpies of formation.
     
  10. Dec 16, 2012 #9

    epenguin

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    Re: Thermochemistry

    Typo from not being able to see original on same screen as typing, I meant ΔHf0
     
  11. Dec 16, 2012 #10
    Re: Thermochemistry

    I know what ΔHf0 means but to solve this question, I think the data is insufficient or am I missing something?
     
  12. Dec 18, 2012 #11
    Re: Thermochemistry

    Can I get some more help?
     
  13. Dec 18, 2012 #12
    Re: Thermochemistry

    You have all the info I believe...Look at hess's law and at the net ionic equation. I have posted what I believe the answer to be...
     

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  14. Dec 19, 2012 #13

    Borek

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    Re: Thermochemistry

    Please don't give final answers, that's not how the forum works.

    When you mix diluted solutions there will be no precipitate. So while you can be right guessing what the question author had on mind, it is not a correct answer to the question as worded.
     
  15. Dec 20, 2012 #14

    epenguin

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    Re: Thermochemistry

    I don't know what ΔHf0 quite means, I'd have to guess so I can't help. But these questions generally involve a cycle, were the Δ's add up to zero if you go round it, and there is one step you have to find the Δ of when given all the others.
     
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