2CLabManual201303

Notes 1 be sure to use only the ammonia buffer

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Unformatted text preview: r to the calcium carbonate solution. Check the pH of the solution using Alkacid paper. You may also want to check the pH of the solution a couple of times during the titration. NOTES: (1) Be sure to use only the ammonia buffer located in the fumehood. Do not use any other buffers that may be found elsewhere in the laboratory. (2) Only add the ammonia buffer to your solution in the fumehood. Five to six drops of Calmagite indicator is sufficient to show the color change at the endpoint. In addition, one can sharpen the endpoint by adding about 1 mL of the solution labeled Na2MgEDTA. The magnesium ion is approximately 40 times more strongly bound to the indicator Calmagite than is the calcium ion. In addition, the calcium ion is approximately 200 times more tightly bound to the ligand EDTA. Thus when EDTA is added to the solution it will preferentially bond to the calcium ion. When the calcium ion has completely reacted, the EDTA will then pull the magnesium ion away from the indicator and the solution will then...
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This note was uploaded on 04/09/2013 for the course CHE CHE 2C taught by Professor Nasiri during the Spring '07 term at UC Davis.

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