Determination of available chlorine in the bleaching solution
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When we measure the available chlorine in the bleaching solution, it turns colorless after a few drops, but the color reappears after some time. Why is that? What should we do?
Book: Compilation of Water Resources and Hydraulics Technology Standards – Water Resources and Water Environment Volume: Analytical Methods http://bbs.hcbbs.com/thread-242473-1-1.html 1. Determination of free chlorine and total chlorine in water quality: N,N-diethyl-1,4-phenylenediamine titration method GB11897—89 2. Determination of free chlorine and total chlorine in water quality: N,N-diethyl-1,4-phenylenediamine spectrophotometric method GB11898—89 Article: Collection of Experience in Chlor-alkali Analysis http://bbs.hcbbs.com/viewthread.php?tid=379750&highlight=%C2%DB%CE%C4%A3%BA%C2%C8%BC%EE%B7%D6%CE%F6%BE%AD%D1%E9%BC%AF%BD%F5 Book: Analysis in the Chlor-alkali Industry http://bbs.hcbbs.com/viewthread.php?tid=335342&highlight=%B7%D6%CE%F6 This post was last edited by Canghai Yili Sha on 2009-4-12 at 14:57
For the calibration of available chlorine, relevant instruments are used for titration, so the situation you mentioned should not occur
Titration is indeed not easy to carry out – it requires stirring, the bottle needs to be shaken a lot, and there should be no residues on the walls; *once you get used to it, it becomes easier
It is normal if it takes more than 5 minutes; if the time is too short, the reaction will be incomplete.
No way, this kind of titration involves slow shaking and quick dripping
Towards the end, shake slowly while adding drops; if the solution becomes colorless and then turns colored again, it means the reaction is not complete and the endpoint has not been reached.