How does the indicator PYROCATECHOL VIOLET work in a titration?

Subject: How does the indicator PYROCATECHOL VIOLET work in a titration?

Date: Sat Jan 13 12:39:50 2001
Posted by Clare
Grade level: 10-12 School: No school entered.
City: No city entered. State/Province: No state entered. Country: No country entered.
Area of science: Chemistry
ID: 979407590.Ch

Message:


I have done a complexiometric titration with copper(II) sulphate against 
EDTA where this indicator was used. it is originally red and turns green 
when the end-point is reached. I would like to know why this works with 
the complex of [Cu(edta)]2- formed to give the green colour. Also, 
pyridine was added to the copper(II) sulphate solution before the 
titration to give an intense blue colour, what is the reason for this? 
This is for a very important chemistry investigation,
thanks you

Re: How does the indicator PYROCATECHOL VIOLET work in a titration?

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