Complexometric (EDTA) titration template

Burette of standard EDTA over a sample buffered at pH 10 with Eriochrome Black T on a white tile; wine red to blue at the end point. A-level / IB / university analytical.

What the template shows

• Find Ca²⁺ and Mg²⁺ (water hardness) by titrating with EDTA at pH 10
• White tile
• Shows the end point: wine red through purple to clear blue (free indicator). Mg²⁺ is needed for a sharp change
• Standard Na₂H₂EDTA; reacts 1 : 1 with every M²⁺
• The last colour change is slow: add dropwise and swirl
• Sample + buffer + indicator
• e.g. 50.0 mL water, 2 mL NH₃/NH₄Cl buffer (pH 10), a few drops of Eriochrome Black T: wine red (Mg–EBT)
• Reaction setup

Drawn with 11 shapes – every one editable in MolDraw.

Sources

• Housecroft & Sharpe, Inorganic Chemistry, 5th ed., Pearson 2018 Textbook