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Homework Help: Titration indicator

  1. Oct 17, 2007 #1
    any one know where I can find the colour range of the indicator Eriochrome black T?
  2. jcsd
  3. Oct 17, 2007 #2


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    H2Ind- (red) pH=6.3 HInd-- (blue) pH=11.5 Ind--- (yellow-orange)

    Mg2+ + HInd-- double arrow MgInd- + H+ wine-red colour before EP buffer pH 6.6-10.5 (NH4Cl/NH3) further titration with EDTA around EP MgInd- (wine-red) + HY--- double arrow MgY-- + HInd-- (blue). It is not easy to see the colour change but it can made better by adding methylred (pH 6.6-10.5) it is yellow and forms with the blue green at the EP point, the change is than from red to green.
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