Spectrophotometric Investigation of Cobalt Chloride Complex Formation in Aqueous Calcium Nitrate–Ammonium Nitrate Melts at T = 328.15 K: Influence of Water Content

  • Milan B. VranešEmail author
  • Snežana M. Papović
  • Slobodan B. Gadžurić


In this work, the absorption spectra of cobalt(II) nitrate and chloride complexes in the composition xCa(NO3)2–(1 – x)NH4NO3–H2O have been investigated in the 400–800 nm range of wavelength at T = 328.15 K and atmospheric pressure p = 101.3 kPa. Spectra were recorded in 0.3 Ca(NO3)2–0.7 NH4NO3–H2O solutions with variable water content (R = H2O/salt mole ratio; Rws = 1.0, 1.2, 1.6 and 2.0), and in xCa(NO3)2–(1 – x)NH4NO3–H2O (x = 0.3, 0.5 and 0.7) solutions where the H2O/salt mole ratio was kept constant (Rws = 2.0). The blue shift of the absorption maximum with increasing water content (Rws) suggests simultaneous coordination by water molecules and nitrate ions. From an analysis of the spectra, it can be concluded that the following complexes: [Co(NO3)4(H2O)2]2−, [Co(NO3)2Cl2]2− and [CoCl4]2− were formed. The overall stability constants of these complexes and the corresponding resolved species spectra were calculated at T = 328.15 K.


Cobalt(II) complexes Water influence Spectrophotometry Calcium nitrate Ammonium nitrate 



This work was financially supported by the Ministry of Education, Science and Technological Development of Serbia under project contract ON172012.

Supplementary material

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Supplementary material 1 (DOC 9779 kb)


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© Springer Science+Business Media, LLC, part of Springer Nature 2019

Authors and Affiliations

  • Milan B. Vraneš
    • 1
    Email author
  • Snežana M. Papović
    • 1
  • Slobodan B. Gadžurić
    • 1
  1. 1.Faculty of Science, Department of Chemistry, Biochemistry and Environmental ProtectionUniversity of Novi SadNovi SadSerbia

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