Hexaprotic acid

Figure 11-6 (d) Experimental points in the titration of 1.430 mg of xylenol orange, a hexaprotic acid, dissolved in 1.000 mL of aqueous 0.10 M NaN03. The titrant was 0.065 92 M NaOH. (fc>) The first derivative, ApH/A V, of the titration curve, (c) The second derivative, A(ApH/A V)/AV, which is the derivative of the curve in panel b. Derivatives for the first end point are calculated in Table 11-3. End points are taken as maxima in the derivative curve and zero crossings of the second derivative. 

EDTA Is a Weak Acid Besides its properties as a ligand, EDTA is also a weak acid. The fully protonated form of EDTA, HeY, is a hexaprotic weak acid with successive pKa values of... 

Figure 11-6a shows experimental results for the manual titration of a hexaprotic weak acid, H A, with NaOH. Because the compound is difficult to purify, only a tiny amount was available for titration. Just 1.430 mg was dissolved in 1.00 mL of water and titrated with microliter quantities of 0.065 92 M NaOH, delivered with a Hamilton syringe. 

EDTA is a hexaprotic system, designated H6Y2+. The highlighted, acidic hydrogen atoms are the ones that are lost upon metal-complex formation. 

EDTA is a hexaprotic system, designated The highlighted acidic hydrogen... 

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