| | SLO | ENG | Cookies and privacy

Bigger font | Smaller font

Show document

Title:Vpliv ionske moči na oksidacijo askorbinske kisline s heksacianoferatnim(III) ionom
Authors:Vidic, Metka (Author)
Petek, Aljana (Mentor) More about this mentor... New window
Brodnjak-Vončina, Darinka (Co-mentor)
Files:.pdf UNI_Vidic_Metka_2012.pdf (1,62 MB)
MD5: F2DA84C536D4B1EB8A3DC54FBBC1CF4F
 
Language:Slovenian
Work type:Undergraduate thesis (m5)
Typology:2.11 - Undergraduate Thesis
Organization:FNM - Faculty of Natural Sciences and Mathematics
Abstract: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.
Keywords:heksacianoferatni(III) ion, askorbinska kislina, ionska moč, kemijska kinetika, spektrofotometrija
Year of publishing:2012
Publisher:[M. Vidic]
Source:Maribor
UDC:546(043.2)
COBISS_ID:19366664 New window
NUK URN:URN:SI:UM:DK:MYF4B1CC
Views:1968
Downloads:88
Metadata:XML RDF-CHPDL DC-XML DC-RDF
Categories:FNM
:
  
Average score:(0 votes)
Your score:Voting is allowed only for logged in users.
Share:AddThis
AddThis uses cookies that require your consent. Edit consent...

Hover the mouse pointer over a document title to show the abstract or click on the title to get all document metadata.

Secondary language

Language:English
Title:The effect of ionic strength on the oxidation of ascorbic acid by hexacyanoferrate(III) ion
Abstract: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.
Keywords:hexacyanoferrate(III) ion, ascorbic acid, ionic strength, chemical kinetics, spectrophotometry


Comments

Leave comment

You have to log in to leave a comment.

Comments (0)
0 - 0 / 0
 
There are no comments!

Back
Logos of partners University of Maribor University of Ljubljana University of Primorska University of Nova Gorica