20.500.12556/DKUM-37416 Vpliv ionske moči na oksidacijo askorbinske kisline s heksacianoferatnim(III) ionom The effect of ionic strength on the oxidation of ascorbic acid by hexacyanoferrate(III) ion Diplomsko delo temelji na eksperimentalnem delu. Izvedli smo eksperiment oksidacije askorbinske kisline s heksacianoferatnim(III) ionom. Ugotavljali smo vpliv ionske moči na hitrost kemijske reakcije. Eksperimentalno delo je potekalo od marca do maja 2012 na Fakulteti za kemijo in kemijsko tehnologijo Univerze v Mariboru, in sicer v laboratoriju za fizikalno kemijo in v laboratoriju za analizno kemijo. Potek kemijske reakcije smo spremljali s spektrofotometričnimi meritvami. Pri valovni dolžini 419 nm smo merili spreminjanje absorbance heksacianoferatnega(III) iona. Ker smo želeli ugotoviti, kako ionska moč vpliva na potek izbrane kemijske reakcije, smo reakcijo izvedli v raztopinah z različnimi koncentracijami natrijevega nitrata ter pri konstantnem pH-ju in temperaturi. Meritve smo opravili s pomočjo Cary 1 UV-Vis spektrofotometra. Vsako K3[Fe(CN)6]-NaNO3 raztopino smo posebej zmešali s H2Asc-HNO3-EDTA raztopino v razmerju 1:1. Meritve absorbance Fe〖(CN)〗_6^(3-) smo uporabili za izračun realne vrednosti konstante reakcijske hitrosti pri konstantnem pH-ju in temperaturi ter pri različnih ionskih močeh raztopine. S pomočjo Debye-Hückel zakona smo nato izračunali konstanto reakcijske hitrosti pri neskončni razredčitvi, ki je neodvisna od ionske moči. Prišli smo do zaključka, da povečana ionska moč pospeši hitrost izbrane reakcije. Ugotovili smo, da so večje opazovane konstante reakcijskih hitrosti pri večji ionski moči. Tako smo z eksperimentom pokazali, da v raztopinah z višjo koncentracijo natrijevega nitrata oksidacija askorbinske kisline s heksacianoferatnim(III) ionom poteka hitreje. Vrednost Z1Z2, ki sta naboja ionov, ki sodelujeta v hitrost določujoči stopnji reakcije, smo dobili 3,04, kar je zelo blizu teoretične vrednosti 3. This diploma thesis is based on experimental work. We performed an experiment of oxidation of ascorbic acid by hexacyanoferrate (III) ion. We tried to find out the effect of ionic strength on the rate of the chemical reaction. The experimental work was carried out between the March and the May 2012 at the Laboratory for Physical Chemistry and at the Laboratory for Analytical Chemistry, at the Faculty of Chemistry and Chemical Engineering, University of Maribor. The progress of the chemical reaction was monitored with spectrophotometric measurements. We measured the variation of absorbance at 419 nm wavelength of hexacyanoferrate(III) ion. We carried out the experiments with various concentrations of sodium nitrate, and at constant pH and temperature, because we wanted to find out how the ionic strength influences the progress of the studied chemical reaction. The measurements were performed with the Cary 1 UV-Vis spectrophotometer. Each K3[Fe(CN)6]-NaNO3 solution was separately mixed with H2Asc-HNO3-EDTA solution, in proportion 1:1. The measurements of absorbance of Fe〖(CN)〗_6^(3-) were used for calculating the real value of reaction rate’s constant at various ionic strengths of the solution, and at a constant pH and temperature. With the help of Debye-Hückel theory we calculated the constant of the reaction rate at infinite dilution, which is independent of ionic strength. We concluded that increased ionic strength accelerates the rate of the studied reaction. We found out that the observed constants of reaction rates are increasing with ionic strength of the medium. This experiment showed that in solutions with higher concentration of sodium nitrate the oxidation of ascorbic acid by hexacyanoferrate(III) ion proceeds faster. The value of Z1Z2 that represent the ions’ charges which take part in the rate-determining step of reaction was 3.04, which is very close to the theoretical value of 3. heksacianoferatni(III) ion askorbinska kislina ionska moč kemijska kinetika spektrofotometrija hexacyanoferrate(III) ion ascorbic acid ionic strength chemical kinetics spectrophotometry true true false [M. Vidic] Slovenski jezik Angleški jezik Diplomsko delo 2012-08-30 07:11:12 2012-09-27 13:20:36 2022-04-23 23:07:30 2021-04-18 03:25:19 2012 0 Maribor 0 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 546(043.2) 19366664 URN:SI:UM:DK:MYF4B1CC UNI_Vidic_Metka_2012.pdf UNI_Vidic_Metka_2012.pdf 1 F2DA84C536D4B1EB8A3DC54FBBC1CF4F 9177540b6ef91f95665416e37497bbd72521db834b4a4370c69458b340196727 3d0c3f05-7c08-11eb-bb7a-00155d0001ca 20.500.12556/dkum/2d909e70-b69e-43a3-a304-d1fcc9eaf066 https://dk.um.si/Dokument.php?lang=slv&id=49288 Fakulteta za naravoslovje in matematiko 0 0 0