EDTA Titration Spectrophotometry

• M²⁺(aq) + Y^4-(aq) --> MY^2-(aq)
• everything is colorless
• detect endpoint with an indicator (CAL)
• red before endpoint, blue at/after
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• Set spectrophotometer to ‘see’ only CAL (610 nm)

• How does finding Volume EDTA needed to reach endpoint help us measure [M²⁺]?

The Spectrophotometer

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• Beer’s Law: Absorbance is proportional to Concentration