Quan Lab 6 - Charne Rutherford Dr.Wei Group 2 Quantitative...

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Charne Rutherford Dr.Wei Group 2 Quantitative analysis 3401 Determination of Water Hardness by EDTA Titration Objective: The purpose of this Lab is to demonstrate how effective the EDTA titration techniques are by determining the hardness of stock solution sample CaCO 3. Materials: 1. Burette, Volumetric Flask, Erlenmeyer flask, pipet 2. 4mM Mg 2+ solution 3. 0.01M EDTA titrant solution 4. NH 3 /NH 4 + , pH 10 buffer 5. Calmagite indicator 6. 2400ppm CaCO 3 stock solution Procedures: 1. Prepare working standard solution 600ppm CaCO3 by pipeting 25mL of the 2400ppm solution into a 100mL volumetric flask. Dilute to mark and mix well. 2. Make a Blank Correction :
Add approximately 25mL of distilled water into an erlenmeyer flask. Pipet exactly 2mL of the 4mM Mg 2+ solution, add approximately 2mL of the NH3/NH4 + buffer, and 12 drops of the indicator solution. Titrate, repeat the titration on a second blank sample and average the results. Try to be as consistent as possible with the color at the endpoint. The two volumes should agree within ±0.20mL.

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