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Help with working out chemical equations

  1. Aug 9, 2005 #1
    im new to this forum, i have used it quite alot for physics, however i need some help with chemistry and was hoping someone could help me work out a few equations i need for a social relevance essay. im doing the essay on forensics chemistry; particularly how gunshot residue is detected. The first equation i need help with is from the Dermal Nitrate Test, and so far i only know the reactants, not the products,

    Nitrocellulose + Diphenylamine + Concn Sulfuric Acid --->
    C6H8(NO2)2O5 + (C6H5)2NH + H2SO4 --->

    i have a couple others i need help with, but im unsure of all the reactants at the moment, so i will post them up when i have them (Sodium Rhodizonate Test & the Modified Griess Test if anyone knows of them)

    thanks alot for any help,
    Last edited: Aug 9, 2005
  2. jcsd
  3. Aug 9, 2005 #2
    diphenylamine is a redox indicator, its purple when oxidized and colorless when reduced.

    the acid helps keep it reduced - the presence of an oxidizer such as nitrocellulose will oxidize the diphenylamine (despite the strong acid) and change color.

    many of the chemical methods used in forensic chemistry make use of redox indicators of varying strengths/preferences. another one that you might be interested in is luminol, which with H2O2, will illuminate when reduced by something such as Fe (thereby used to detect blood).
  4. Aug 11, 2005 #3
    wow thanks quetzacoatl, i hadnt seen anything about the 'luminol test', however it sounds like it will fit in nicely with my essay.

    Anyone else able to offer any assistance? particularly in the equations as i am hopeless at doing them, which is not good as according to my chem teacher they are important for this essay,
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