Chemical Forums
Chemistry Forums for Students => Inorganic Chemistry Forum => Topic started by: aj3537 on November 25, 2008, 02:11:11 PM
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I am writing a term paper on the different chelators: EDTA, BAL, and D-Penicillamine. In the paper, they compare different metals (lead, zinc, calcium, copper, and iron) and their affinity towards the different chelators.
M2+ +Ln- -> [M(L)]2-n ∆Ecomp+ E([M(L)]2-n) – E(Pb2+) – E(Ln-)
[Pb(H2O)8]2+ + [M(L)]2-n-> [Pb(L)]2-n + [M(H2O)]2+
∆Eexch= E([M(H2O)8]2+) + ([Pb(L)]2-n) – E([M(L)]2-n) – E([Pb(H2O)8]2+)
They give these equation in the paper. Can some simply explain what complexation and exchange energy is and how these values work since lead is favored over the other metals:
EDTA
comp ca -803 fe -969 cu -950 zn -925 pb -790
exch ca -9.8 fe 24 cu 12 zn 0.4 pb 0
BAL
comp ca -508 fe -679 cu -700 zn -671 pb -557
exch ca -70 fe -33 cu -6 zn -21 pb 0
D-Penicillamine
comp ca -522 fe -698 cu -702 zn -676 pb -561
exch ca -60 fe -19 cu -8 zn -19 pb 0 kcal/mol