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Hydrogen peroxide/ sulfuric acid mixture

  1. Sep 24, 2012 #1
    Hi, I'm not sure what I just created. First I mixed sodium iodide with hydrochloric acid. Then to that I added a hydrogen peroxide/ sulfuric acid mixture (thinking it was just hydrogen peroxide). It seems a black precipitate is forming.

    I was trying to make potassium iodide using an inherited box of mystery chemicals (probably not a good idea, granted) from a previous teacher for elephant toothpaste demo.
  2. jcsd
  3. Sep 24, 2012 #2


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    Last edited by a moderator: Sep 25, 2014
  4. Sep 24, 2012 #3
    It is similar, yes. I just sort of did a double take when I realized I wasn't working with hydrogen peroxide, but some mixture of h2o2 and sulfuric acid. I was thinking maybe sulfur precipitated as well given the smell. It also has a much finer grain and slightly greyish color.
  5. Sep 24, 2012 #4


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    Sulphur as far as I remember, is yellow colour. Hydrogen Peroxide is usually mixed with little sulphuric acid or phosphoric acid or glycerine, as they work as negative catalyst in the disproportionation reaction, in which Peroxide converts into water and dioxygen. (Considering I remember I had been taught)

    As for Sulphur, I am not sure that Sulphuric acid has enough strength to oxidise Peroxide and get reduced itself to form Sulphur, so chances of sulphur formation is nil.
  6. Sep 24, 2012 #5
    Ok, I guess the sulfuric acid wasn't really part of it after all.
  7. Sep 24, 2012 #6
    Please don't brush an elephant's teeth with your concoction.
  8. Sep 25, 2012 #7


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    Don't worry, elephants' teeth are hard to reach. He won't bother. :wink:
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