NotesFAQContact Us
Search Tips
Peer reviewed Peer reviewed
Direct linkDirect link
ERIC Number: EJ832505
Record Type: Journal
Publication Date: 2009-Apr
Pages: 4
Abstractor: As Provided
Reference Count: 16
ISSN: ISSN-0021-9584
Spectrophotometric Determination of Iron(III)-Glycine Formation Constant in Aqueous Medium Using Competitive Ligand Binding
Prasad, Rajendra; Prasad, Surendra
Journal of Chemical Education, v86 n4 p494-497 Apr 2009
The formation constant of iron(III) complex with glycine (Gly) ligand in aqueous acidic medium (0.2 M HNO[subscript 3], I = 0.2 M at 28 plus or minus 1 degree C) was determined spectrophotometrically in which a competing color reaction between Fe(III) and SCN[superscript -] was used as an indicator reaction. Under the specified conditions Fe(III) formed 1:1 complexes, [Fe(SCN)][superscript 2+] and [Fe(Gly)][superscript 2+], with both of these ligands. The molar absorption coefficient and the formation constant of the [Fe(SCN)][superscript 2+] complex were determined graphically as well as through dynamic optimization of six parallel equations using Solver tool in Excel. Values thus obtained were subsequently used to calculate concentrations of uncoordinated iron(III) and glycine in the mixed-ligand solution. The principal advantage of the proposed method is that it offers a simple and convenient approach for an undergraduate laboratory demonstration of quantitative comparisons of formation constants using an inexpensive spectrophotometer and Excel software that are readily available in most teaching laboratories. (Contains 2 figures and 2 tables.)
Division of Chemical Education of the American Chemical Society. Subscription Department, P.O. Box 1267, Bellmawr, NJ 08099-1267. Tel: 800-691-9846; Tel: 856-931-5825; Fax: 856-931-4115; e-mail:; Web site:
Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education
Audience: Teachers
Language: English
Sponsor: N/A
Authoring Institution: N/A