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      11 Jun
    Ajay S. Satpute

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Chemical and Process Engineering Resources

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Category: Experimentation and Testing
Question: What is a common source of error in determining the percent spent caustic in refinery applications?
Keywords: spent,caustic,laboratory,prediction,measurement,error,methyl,orange,phenolphthalein,endpoint
Answer: In titrations, a common error made is that the technicians stop at the phenolphthalein endpoint (which is incorrect) rather than the methyl orange endpoint (which is correct). Stopping the titration too soon can cause the results to be grossly under-reported.Equation (1): 2NaOH + H2S -> Na2S + 2H20 Equation (2): Na2S + H2S -> 2NaSH Overall Equation: NaOH + H2S -> NaSH + H2O