Determination of Mn by titration with EDTA
How can you determine the concentration of Manganese Mn ions in solution?
you can determine Mn+2 by EDTA (Ethylene diamine tetra acetic acid) titration
Determination of Manganese(ii) ions by Direct EDTA Titration using Eriochrome Black T as indicator
Manganese Mn
Atomic Weight 54.938049
Density 7.47 g/cm3
Melting Point 1246 °C
Boiling Point 2061 °C
PRINCIPLE:
Manganese ions (Mn+2) concentration in a sample can be determined quantitatively by
complexometric direct titration with EDTA at pH 10. Eriochrome black T is used as an
indicator; it is Blue when it is free (Hln2-) and wine-red when complexed with Zinc.
Like all manganese(II) containing species, it readily undergoes oxidation in alkaline
media to form products of uncertain stoichiometry. For this reason, manganese (II) is
always titrated in the presence of a reducing agent such as ascorbic acid or hydroxylammonium
chloride.
REAGENTS:
1- Manganese ions solution (analyte)
2- Hydroxylammonium chloride or ascorbic acid
2- pH10 buffer solution
3- Eriochrome black T indicator
4- 0.01 M EDTA solution
m
PROCEDURE:
1- Pipette 25.0 mL of Manganese ion solution in a 250.0 mL conical flask and
dilute to about 100.0 mL with distilled water. Add 0.25 g hydroxylammonium
chloride or ascorbic acid [this is to prevent oxidation of Mn(II) ions].
2- Add 2‒3 mL of pH10 buffer solution and 30-40 mg of Eriochrome Black T
indicator.
3- Titrate with 0.01 M EDTA until the color changes from wine-red to pure
blue. Record the used volume (as V EDTA).
4- Repeat the titration twice.
Atomic weight of Manganese = 54.94 g/mol
REAGENTS:
1- Manganese ions solution (analyte)
2- Hydroxylammonium chloride or ascorbic acid
2- pH10 buffer solution
3- Eriochrome black T indicator
4- 0.01 M EDTA solution
m
PROCEDURE:
1- Pipette 25.0 mL of Manganese ion solution in a 250.0 mL conical flask and
dilute to about 100.0 mL with distilled water. Add 0.25 g hydroxylammonium
chloride or ascorbic acid [this is to prevent oxidation of Mn(II) ions].
2- Add 2‒3 mL of pH10 buffer solution and 30-40 mg of Eriochrome Black T
indicator.
3- Titrate with 0.01 M EDTA until the color changes from wine-red to pure
blue. Record the used volume (as V EDTA).
4- Repeat the titration twice.
Atomic weight of Manganese = 54.94 g/mol