In Part B, we determined the water hardness of a water sample by combining the water sample with a 10.00 mL sample of calcium chloride, then titrating with EDTA. If we substituted distilled water for the water sample, how would our titration have been different? Would the volume of EDTA required to reach the end point have been greater than, less than, or the same as the volume we used with our combined sample? Explain.
It's difficult to know how to answer this since I don't know what part A was all about. Also I don't know how much Ca ion is added with a 10.00 mL aliquot. My best guess is that if you add CaCl2 to a sample being titrated with EDTA at a pH of 10, that results will be higher than those when no extra CaCl2 has been added before the titration. I found a web site that explains all about EDTA titrations for the hardness of water but I lost it in trying to transfer it to this post. You can find thousands of places on the web by Googling "determination of hardness of water by EDTA".
