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roselin

  • 2 years ago

what does the following mean? Calculate single ion activity coefficients for Cs^+, Cd^2+,Al^3+ and dissolved H2CO3 as a function of ionic strength for 10^-4 lessthan equal I lessthan equal to1?

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  1. aaronq
    • 2 years ago
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    they want the activity coefficients for the different ions considering the ionic strength given

  2. roselin
    • 2 years ago
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    so from 10^-4 to 1?

  3. roselin
    • 2 years ago
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    i am using the davies equation to calculate it, so each time I have to change the ionic strength th?

  4. aaronq
    • 2 years ago
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    hm no that doesn't seem right. i don't know what they mean by \(10^{-4} \leq 1\), it doesn't make sense.

  5. roselin
    • 2 years ago
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    its \[10^{-4}\le I \le1\]

  6. aaronq
    • 2 years ago
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    oh, i thought you typed the same thing twice accidentally. I guess they want it within that range? thats a large range though. I would graph it

  7. aaronq
    • 2 years ago
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    on excel of course

  8. roselin
    • 2 years ago
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    we have to calculate and plot it

  9. aaronq
    • 2 years ago
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    i guess do a few points for each ion and then plot it

  10. roselin
    • 2 years ago
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    can I show you the full question ? please tell me what I should do

  11. aaronq
    • 2 years ago
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    plug it into the formula? \(log\;\gamma=0.5Z^+_0Z^-_0.. etc\) it's kinda weird though because they don't give you the negative counter ion

  12. roselin
    • 2 years ago
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    if I were to do this manually using that given range, how would I approach it?

  13. aaronq
    • 2 years ago
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    you would calculate the coefficient for several points (ionic strengths) do 3 or 4, then plot these. Activity coefficient on the y axis and ionic strength on the x axis (although you can do on which every way you want)

  14. aaronq
    • 2 years ago
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    it's much easier if you do it in excel though

  15. roselin
    • 2 years ago
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    yes, that is where I am having problem.

  16. roselin
    • 2 years ago
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    like that range is between 10^-4 to 1 right?

  17. aaronq
    • 2 years ago
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    yep thats the range of "I" they gave

  18. roselin
    • 2 years ago
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    how would I calculte that in excel though?

  19. roselin
    • 2 years ago
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    if I do it manually then can I chose to do something like I= 10^-4,10^-3, 10^-2 and 10^-1?

  20. roselin
    • 2 years ago
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    choose**

  21. aaronq
    • 2 years ago
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    yeah thats fine

  22. aaronq
    • 2 years ago
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    for excel you need the x data point and the y data point the x you can just make up: 10^4, 10^3 then for the y you have to use the result from the equation, so you would type up the equation and use the x data points, then fill it. If you're not familiar with excel trying it this way might take you awhile

  23. roselin
    • 2 years ago
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    okay, thank you so much.

  24. aaronq
    • 2 years ago
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    no problem, good luck!

  25. roselin
    • 2 years ago
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    thanks :-)

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