86. What Is A Common Source Of Error In Determining The Percent Spent Caustic In Refinery Applications?
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 2NaOH + H2S -> Na2S + 2H20 Equation Na2S + H2S -> 2NaSH Overall Equation: NaOH + H2S -> NaSH + H2O
