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I am attempting to preform this experiment. Chemistry isn't really my cup of tea, so I have a couple questions.

The instructions say to provide 40µA per cm2, where does that number come from?

The TIO material I'm using has a different resistance than the glass listed, will that change anything?

All the pt wire I could find was very pricy so I though I would use a graphite electrode instead, but all I can find is carbon electrodes. Is that close enough?

Here is the list of materials I have come up with, let me know if any of them are wrong.

Thank you! I'm really excited about attempting this, hopefully I can pull it off.

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  • $\begingroup$ You can't really make an electrode out of just graphite. It would fall apart. To make a carbon paste electrode (i.e. a carbon electrode) you mix graphite with a binder. en.wikipedia.org/wiki/Carbon_paste_electrode $\endgroup$ – MaxW Dec 22 '15 at 23:55
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    $\begingroup$ Ah. So when it says you can substitute a graphite electrode it really means carbon. $\endgroup$ – RedHatter Dec 22 '15 at 23:57
  • $\begingroup$ A fine point here is that there are a lot of allotropes of carbon. Diamond and graphite the best known. Any sort of "carbon electrode" would conduct electricity and that is all you care about. An "electrode" made from diamond and a binder would still be carbon but it would be useless since it wouldn't conduct electricity. en.wikipedia.org/wiki/Allotropes_of_carbon $\endgroup$ – MaxW Dec 23 '15 at 2:09
  • $\begingroup$ Carbon and Graphite are the same thing in respect to electrodes, though I understand the frustration of their ambiguous language. $\endgroup$ – A.K. Dec 23 '15 at 3:48
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You pose a series of questions. Let me attempt to answer them all:

The instructions say to provide 40µA per cm2, where does that number come from?

This comes from an article of Itaya and coworkers where they studied the electrochemical synthesis of Prussian Blue. (http://pubs.acs.org/doi/abs/10.1021/ja00382a006) In fact; the website in your question refers to an article in the Journal of Chemical Education (http://pubs.acs.org/doi/abs/10.1021/ed075p881) which in turn refers to the JACS article above.

From my understanding, this number should be seen as an experimental condition. It is given so that the experiment is reproducible.

The TIO material I'm using has a different resistance than the glass listed, will that change anything?

The material you are using has roughly twice the resistivity as compared to the one used in the experiment. In principle, this would not pose too much of a problem. You can tune your electric system using the variable resistor. Just make sure you stick to 40µA per cm2.

All the pt wire I could find was very pricy so I though I would use a graphite electrode instead, but all I can find is carbon electrodes. Is that close enough?

This has already been answered by A.K. The carbon flat electrode should work fine. Though I am not sure whether you can use it repetitively (in multiple experiments).

As a boost of confidence. The procedure you are using is both reported in JACS as well as in J. Chem. Ed.; it should work. If you are conducting this experiment at your university or high school, perhaps someone can give you a copy of the articles to which the website refers. The experimental procedures in these articles can be really helpful in preparing your experiment. Best of luck!

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