[psyche115]

Hi there,

I had a few questions about this experiment that I'm sure about. I understand that the blank for the standardization titration of KMNO4 is sulfuric acid but what is the blank for the titration of the iron unknown?? Also, is the equivalence point of the titration just when there is the first instance of a pink colour for 30 seconds? For the filtration of the KMNO4 solution, is the dark solid being filterd off the MnO2?? Could you please verify these questions/answers as soon as you can.

Thanks!

[jakowyna]

The Equivalence point is the point at which chemically equivalent amounts of MnO4- and Fe2+ have reacted. Therefore its when you have add the same ratio of MnO4- and Fe2+ as the amount of number moles from the chemical equation.

You can never be 100 percent sure when the equilvalence point has been reach , however an accurate way of deteriming it is using the end point of the titration. The end point is when one drop of MnO4- produces a constant pink colour, due to the excess MnO4- ion.

MnO2(s) is a blackish or brownish solid, so it is most likely to be MnO2(s).

[Borek]

http://www.titrations.info/permanganate-titration-iron