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  1. #11
    Photo Engineer's Avatar
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    Thanks. This is all very interesting. I wish I could see more. Wonderful stuff.

    PE

  2. #12

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    Quote Originally Posted by Photo Engineer View Post
    Great work. Congratulations.

    At that concentration of NaBr after the wash, at 10 deg C (a good wash temp), the vAg would be about +37 and at 40 deg C (a good coating temp) it would be about +67 mv.
    PE
    Can you show the math behind these calculations?

    Thanks,

    Ray

  3. #13
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    Quote Originally Posted by Ray Rogers View Post
    Can you show the math behind these calculations?

    Thanks,

    Ray
    Ray;

    I have posted this fully in another thread. This uses the Debye Huckle and the Nernst equations. They can be found here: http://en.wikipedia.org/wiki/Debye%E...Cckel_equation and here: http://en.wikipedia.org/wiki/Nernst_equation

    This is a very laborious calculation from very complex equations. I hope it is of use to you.

    PE

  4. #14

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    Quote Originally Posted by Photo Engineer View Post
    Ray;

    I have posted this fully in another thread. This uses the Debye Huckle and the Nernst equations. They can be found here: http://en.wikipedia.org/wiki/Debye%E...Cckel_equation and here: http://en.wikipedia.org/wiki/Nernst_equation

    This is a very laborious calculation from very complex equations. I hope it is of use to you.

    PE
    Yes, I recall the discussion.

    I was hoping to see the actual calculation done for a real world emulsion problem... the wiki dissertations are not that easy to follow or, at least, do not hold my attention long enough...

    However, I am sure if I saw them actually being used to crunch out the numbers you gave, my attention span would quadruple...
    at the very minimum!

    I think you once said you could do the conversion using of the Debye Huckle and Nernst equations rather easily,
    so I thought you might have a "system" that you could share with the more mathematically challenged.

    Hummm, that... or a copy of your "cheat sheet" that converts these units to vAg.
    Last edited by Ray Rogers; 06-23-2010 at 06:41 PM. Click to view previous post history.

  5. #15
    Photo Engineer's Avatar
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    I did post a cheat sheet with concentration vs vAg at 20 and 40 deg C. It was appended to one of those threads.

    And, the equations I use are similar to those in the references I gave above. It is a page or more of calculations. They involve PKSP values for each halide involved, Junction Potential calculations, natural log functions and conversion of temperature to Kelvin and then offsetting the value of all based on degrees K. And, before you get to vAg you have to know the negative log of the silver ion concentration (or pAg) in a manner similar to pH calculations.

    My "system" is having had to do it daily for about 15 years.

    PE

  6. #16

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    an old Stones song... about how white my shirts can be...

    Oh, Kaye...

  7. #17

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    I started an Excel speradsheet to do these calcs. I can't remember if I finished it. I'll post it if I did. Or PE may have a spreadsheet to post. (Although I think PE once told me he uses a VB program to do the calcs.)
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  8. #18

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    Quote Originally Posted by Kirk Keyes View Post
    I started an Excel speradsheet to do these calcs. I can't remember if I finished it. I'll post it if I did. Or PE may have a spreadsheet to post. (Although I think PE once told me he uses a VB program to do the calcs.)
    In a real world, that would be both Useful and Excel...lent!

  9. #19
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    With apologies to Ray

    My data for vAg calculations were deleted from APUG during an argument on-line here about two years ago with another APUG member. It appears that they are GWTW and I apologize. I will have to recreate them entirely from scratch if they are to be in any useful form.

    And, the spreadsheet of data was erased by me before posting because APUG did an abysmal job of handling the tabbed data in rows and columns.

    Here is the graph generated from the data. Sorry that it is partly incomplete, but I have a lot of work to do to clean it up from my Excel spreadsheet. It is the only JPG file that I have on-hand.

    PE
    Attached Thumbnails Attached Thumbnails NaBr vAg.jpg  

  10. #20

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    Quote Originally Posted by Photo Engineer View Post
    With apologies to Ray
    Thanks Ron.

    The reason I enquired was because the VAg values for NaBr you mentioned earlier in this thread are all positive... however those seen here (in the jpeg) for example, are negative.

    While conc. and temps do differ,
    I was just wondering if perhaps....

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