Chemical Reduction of Gold(III) Bromide Complexes Using Sodium Nitrite - Kinetic Aspects

• Autorzy: Pacławski K.

Identyfikatory

DOI

10.24425/amm.2020.132805

• Języki publikacji: EN

Abstrakty

EN

In this work, the spectrophotometric studies on the kinetics of redox reaction between gold(III) bromide complexes and sodium nitrite, were carried out. From the kinetic curves collected under different conditions of reactants concentration, addition of bromide ions, temperature, pH and ionic strength, corresponding rate constants have been determined. The obtained results suggest the complex path of the [AuBr₄]^- reduction consisting of two parallel, bimolecular reactions where different reductant species (HNO₂ and NO₂^-) take place and consecutive step with the metallic gold production. The second-order rate constants at 20°C are equal to 2.948 and 0.191 M^-1·s^-1, respectively. The values of activation enthalpy and activation entropy for the first and the second parallel step of the reaction were found to be ΔH^‡ = 29.18 kJ·mol^-1 and ΔS^‡ = –13.95 J·mol^-1·K, and ΔH‡ = 40.75 kJ·mol^-1 and ΔS‡ = –31.06 J·mol^-1·K, respectively. It was found that the reaction accelerates significantly with the increase of pH and is inhibited with the increase of Br^- concentration. The substitutive, inner-sphere mechanism of electron transfer in the studied system was also suggested.

Słowa kluczowe

EN

kinetics; mechanism; redox; gold complexes; sodium nitrite

• Wydawca: Institute of Metallurgy and Materials Science of Polish Academy of Sciences ; Committee of Materials Engineering and Metallurgy of Polish Academy of Sciences
• Czasopismo: Archives of Metallurgy and Materials
• Rocznik: 2020
• Tom: Vol. 65, iss. 2
• Strony: 667--675
• Opis fizyczny: Bibliogr. 26 poz., rys., tab., wzory

Twórcy

autor

Pacławski K.

• AGH University of Science and Technology, Faculty of Non-Ferrous Metals, Laboratory of Physicochemistry and Metallurgy of Non-Ferrous Metals, Al. A. Mickiewicz 30, 30-059 Kraków, Poland

Bibliografia

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Uwagi

EN

1. This work was supported by the National Centre for Research and Development (Poland), The National Fund for Environmental Protection and Water Management (NFEP&WM) (Grant no. GEKON2/05/266425/18/2015).

PL

2. Opracowanie rekordu ze środków MNiSW, umowa Nr 461252 w ramach programu "Społeczna odpowiedzialność nauki" - moduł: Popularyzacja nauki i promocja sportu (2020).