Dear members,
I am a Finnish conservation student currently working with marine
arcaheological iron.
I have a basic question to make:
I am analysing the chloride samples with a titrator that gives the readings
in moles per litre.
I haven't managed to convert the readings to mg/l.
I have samples of 5 ml in 100 ml of water.
For example, the first sample I analysed from the wash solution (1% KOH) of
an anchor gave me 0.19 M. I tried to convert this to mg/l by multiplying the
reading with the molecular weight of Cl:
0.19 mol/l x 35,5 g/mol = 6,75 g/l...which would be 6750 mg/l.
That reading can't be right.
I did not add nitric acid to lower the pH, because our chemist thought it is
not important. However, I have experience in using the gran paper (samples
analysed with the 'argentometrie potentiometrie') and I was told that it is
essential to add the nitric acid to eliminate the interference of OH- ions.
I tried again and added the nitric acid enough to obtain a pH of 2, but the
titrator could not give me any reading...and it does that when the chloride
concentration has gone too high.
I have also used the kit (Merck) for measuring chlorides. According to that
tests the concentrations would be (as I also expected them to be in the very
beginning of the washing process) from 20 to 45 mg/l.
I would be extremely grateful, if somebody could help me with this matter.
Sincerely
Saila Sorsa
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Saila Sorsa Tel: +358 (0)9 - 556 320
Linnoituksentie 10 M 116 Mobile: +358 (0)50 - 573 6697
00940 HELSINKI e-mail: [log in to unmask]
Web site : http://www.helsinki.fi/~shjsorsa/
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