Eriochrome Black T Color Range: Find It Here

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SUMMARY

The discussion focuses on the color range of the indicator Eriochrome Black T, specifically its transitions at various pH levels. At pH 6.3, the indicator appears red (H2Ind-), transitioning to blue (HInd--) at pH 11.5, and finally to yellow-orange (Ind---). The color change during titration with Mg2+ and EDTA is highlighted, particularly the wine-red color of MgInd- at the equivalence point (EP) between pH 6.6 and 10.5. The addition of methyl red enhances visibility of the color change from red to green at the EP.

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  • Understanding of acid-base indicators and their pH ranges
  • Familiarity with titration techniques and equivalence points
  • Knowledge of magnesium ion chemistry in titrations
  • Basic principles of colorimetric analysis
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  • Research the properties and applications of Eriochrome Black T in analytical chemistry
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higherme
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any one know where I can find the colour range of the indicator Eriochrome black T?
 
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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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