From: Carl Hinote (CHinote@usd259.net)
Date: Fri Jan 02 2004 - 14:22:28 EST
Next message: Loretta Ekoniak: "[Channel-talkchemistry] first day"
Wow! I am sorry I am not quite prepared for this question. Read the
attached article, hopefully it will help.
-----Original Message-----
From: andrew wilson [mailto:andrewwilson550@hotmail.com]
Sent: Tuesday, December 30, 2003 6:03 PM
To: channel-talkchemistry@learner.org
Subject: [Channel-talkchemistry] Re:Chemistry Question
Dear Sir
I need some help please!!!
I need some help on how to tackle the following question on Back
Titrations.I have tried to find some information in inorganic texts but
have been unable to find a similar example.
Procedure
To 10cm3 of solution A add 25cm3 (xcess) of the EDTA solution and 10cm3
of the NH4OH/NH4Cl buffer solution and titrated the xcess EDTA with
0.01mol cm3 zinc solution using Erichrome Black indicator.
To a second 10cm3 aliquot of solution A added 25cm3 (xcess)EDTA and
10cm3 of NH4Ac/Acetic acid buffer solution (pH approx 4.5) and next
added 50cm3 of alcohol and titrated again with the zinc solution.
Dithizone was used as the indicator.
I need to be able to
1) Calculate the amount of free (xcess EDTA) present
2) then calculate,by difference, the concentration of magnesium and zinc
present in solution A.
Any guidance would be greatly appreciated.
Best wishes
Andrew
_____
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