using Ethylenediaminetetraacetic acid or EDTA. EDTA is a compound that is often used to separate metal ions from aqueous solution. Furthermore, the complexometric indicator Eriochrome Black T is used in this titration because a color change occurs when the reaction has concluded. The indicator is chosen due to the fact that when EDTA reacts with Ca2+ a complex is formed. In order to ensure a complete reaction, a buffer was added to fully deprotonate the EDTA molecule. To determine the concentration
A 25.00 mL aliquot (a portion or part) of the standard calcium solution reacts with 27.25 mL of the EDTA solution. What is the molarity of the EDTA? 3. Ca2+ concentration in an unknown solution CaCO3 reported as ppm CaCO3. A 50.00 mL unknown solution requires 25.55 ml of the standardized EDTA solution for complete reaction. What is the Ca2+ concentration in the unknown reported as ppm CaCO3 ? Calculations 1. To determine the titrant volumes
AA-Concentration of Calcium and Magnesium ions (ppm) 1.665 ppm 170.5 ppm 347.9 ppm 291 ppm EDTA-Concentration of all 2+ ions 60 ppm 160 ppm 320 ppm 200 ppm Sample Calculation: Using the formulas displayed on the graphs above and the values given by the AA instrument hardness was calculated. Calcium Concentration: AA Analysis y=0.0069x+0.0078 0.0124=0.0069x+0.0078 x=0.666 ppm Ca 0.666ppm Ca2+ x (100CaCO3/1 mole)= 1.665 ppm hardness EDTA M 1V 1=M 2V 2 (2.0x10^-4)(3 drops)=M 2(1 drop)=6.0x10^-4 M Conversion to ppm