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Title:Tvorba koordinacijskih spojin med osnovnimi gradniki taninov in Fe(II) : diplomsko delo univerzitetnega študijskega programa I. stopnje
Authors:ID Frešer, Franjo (Author)
ID Bren, Urban (Mentor) More about this mentor... New window
ID Hostnik, Gregor (Comentor)
Files:.pdf UN_Freser_Franjo_2020.pdf (2,97 MB)
MD5: CE1A00AE99B9201C0F3628AC82E0A42A
PID: 20.500.12556/dkum/9cdc3c33-92f0-402c-aaf8-9068d6e0a58d
 
Language:Slovenian
Work type:Bachelor thesis/paper
Typology:2.11 - Undergraduate Thesis
Organization:FKKT - Faculty of Chemistry and Chemical Engineering
Abstract:V diplomskem delu smo proučevali vpliv pH-ja na tvorbo koordinacijske spojine, ki nastane pri reakciji galne kisline z železovimi(II) ioni. Z uporabo UV/Vis spektroskopije smo izmerili spekter, ki nastane pri tvorbi koordinacijske spojine, in preverili reverzibilnost reakcije. Z meritvijo absorbanc (λ = 560 nm, T = 25 °C) petih nizov vzorcev pri petih različnih pH-jih (3,52 – 5,50) smo konstruirali Jobov diagram, pri čemer so bile skupne koncentracije posameznih raztopin galne kisline in železovih(II) ionov enake 0,5 mmol/L. Na podlagi oblike krivulj smo pokazali, da je stehiometrija tvorjene koordinacijske spojine enaka 1:1. Pri reakciji se je pH vzorcev pri vseh nizih raztopin nekoliko znižal, kar nakazuje, da se pri reakciji sproščajo oksonijevi ioni. Eksperimentalno določenim točkam Jobovega diagrama smo globalno prilegali dva modela. Z modelom A smo predpostavili le, da v raztopini reagirata galna kislina in železovi(II) ioni, medtem ko je model B pri reakciji upošteval tudi protolitsko ravnotežje galne kisline. Z obema modeloma smo določili molarni absorpcijski koeficient in konstanto ravnotežja tvorbe koordinacijske spojine, s katero smo nato izračunali standardno reakcijsko Gibbsovo prosto energijo. Z modelom B, ki je predpostavil, da je reaktivna zvrst H2GA2-, smo izračunali še ravnotežne koncentracije posameznih zvrsti galne kisline, železovih(II) ionov in nastale koordinacijske spojine. Z njimi smo določili odvisnost ravnotežnih koncentracij (in deležev) posameznih zvrsti galne kisline od molskega deleža galne kisline in pH-ja raztopine. Podobno smo pokazali, koliko železa je pri različnih sestavah (in pH-jih) raztopine vezanega v koordinacijsko spojino.
Keywords:galna kislina, železovi(II) ioni, koordinacijska spojina, Jobov diagram, UV/Vis spektroskopija, modeliranje
Place of publishing:Maribor
Place of performance:Maribor
Publisher:[F. Frešer]
Year of publishing:2020
Number of pages:X, 49 str.
PID:20.500.12556/DKUM-76865 New window
UDC:543.2:456(043.2)
COBISS.SI-ID:33661699 New window
NUK URN:URN:SI:UM:DK:2BKIQNB5
Publication date in DKUM:08.10.2020
Views:1303
Downloads:147
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FKKT
:
FREŠER, Franjo, 2020, Tvorba koordinacijskih spojin med osnovnimi gradniki taninov in Fe(II) : diplomsko delo univerzitetnega študijskega programa I. stopnje [online]. Bachelor’s thesis. Maribor : F. Frešer. [Accessed 13 April 2025]. Retrieved from: https://dk.um.si/IzpisGradiva.php?lang=eng&id=76865
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Licences

License:CC BY-NC-ND 4.0, Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Link:http://creativecommons.org/licenses/by-nc-nd/4.0/
Description:The most restrictive Creative Commons license. This only allows people to download and share the work for no commercial gain and for no other purposes.
Licensing start date:20.07.2020

Secondary language

Language:English
Title:Formation of coordination complexes between Fe(II) and basic tannin building blocks
Abstract:In this bachelor thesis we studied the influence of pH on the formation of the coordination compound formed by the reaction of gallic acid with iron(II). Using UV/Vis spectroscopy, we determined the spectrum of the coordination compound. We also checked the reversibility of the reaction. By measuring the absorbances (λ = 560 nm, T = 25 °C) of five sets of samples with five different pH values (3,52 – 5,50), we constructed a Job plot, where the total concentrations of gallic acid and iron(II) were equal to 0,5 mmol/L. Based on the shape of the curves, we showed that the stoichiometry of the formed coordination compound equals to 1:1. During the reaction, the pH of the samples decreased slightly in all sets of solutions, which indicates that protons are released during the reaction. We globally fitted two models to the experimentally determined points of the Job plot. Model A assumed only that gallic acid and iron(II) reacted in the solution, while Model B also considered the protolytic equilibrium of gallic acid in the reaction. Using both models, we determined the molar absorption coefficient and the equilibrium constant of the formation of the coordination compound, which was than applied to calculate the standard Gibbs reaction free energy. Using model B, which assumed that the reactive species is H2GA2-, we also calculateted the equilibrium concentrations of individual gallic acid species, iron(II) and the resulting coordination compound. With them we determined the dependence of equilibrium concentrations (and portions) of individual gallic acid species on the molar fraction of gallic acid and on the pH of the solution. Similarly, we showed how much iron is bound in the coordination compound at the different compositions (and pH values) of the solutions.
Keywords:gallic acid, iron(II), coordination complex, Job plot, UV/Vis spectroscopy, modeling


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