Answers by visitors named: :kkk:

Here are my thoughts: 1. Increase, because ferric ions will cause the endpoint to become violet instead of a clear blue. Hence, greater amount of EDTA will be used thus increasing the calculated ppm CaCO3 2. I have no idea... 3. Decrease, because in the absence of MgCl2 in the solution, the endpoint comes too early. Hence, less of the EDTA titrant would be added. 4. Increase, since less of the I3- will be formed and less of the Na2S2O4 titrant would be needed. less Na2S2O4 used = higher Na2S2O4 concentration = higher Cu concentration = higher ppm Cu

I think something is wrong with your problem...

how can potentiometric titration be useful in titration in non-aqueous media?