The redox titration of Fe (II) ions with K2Cr2O7 using a potentiometry method the effect of EDTA and SCN- ligands

Abstract

Complexometric titration is often used for determining the metal content, either through direct titration or back titration. This study aimed to investigate redox titration between Mohr salt solutions and potassium dichromate in an acidic atmosphere in the pH range 2. The results showed that the reaction proceeded effectively at pH 2, with Mohr's salt solution acting as titrant. Furthermore, experiments were conducted to compare the effectiveness of EDTA ligands and SCN- ligands in improving the sharpness of the Fe2+/ Cr2O7 2- redox titration curve at pH 2. Results show that EDTA ligands are more effective than SCN- ligands in improving the sharpness of the titration curve. However, it should be noted that the addition of EDTA ligands can shift the equivalent point volume earlier, so adjustments need to be made in redox titration analysis. The use of EDTA and SCN- ligands in the redox titration of Fe(II) ions with K2Cr2O7 using a potentiometric method help in forming stable and detectable complexes with Fe(II), leading to clear and reliable potentiometric measurements. Research has also shown that adding excess moles of EDTA to total Fe (II) ions can decrease redox potential in Fe2+/ Cr2O7 2- systems. Based on the volume at the equivalence point, the Fe2+ ion in Mohr salt is 14.30%. with an average titration error of less than 0.30%. These results highlight the role of EDTA ligands in redox titration analysis and their impact on redox potential changes. The use of EDTA and SCN- ligands in the redox titration of Fe(II) ions with K2Cr2O7 using a potentiometric method help in forming stable and detectable complexes with Fe(II), leading to clear and reliable potentiometric measurements. Keywords: complexation, EDTA, ligands, redox potential, pH