Download Electric conductivity of Cu (NO ) 2∙3 Н2 О solutions in

Section 5. Physical chemistry
Mamyrbekova Aigul Kumekbaevna,
сandidate of chemical science, associate professor,
M. Auezov South Kazakhstan state university
E‑mail: [email protected]
Mamitova Aigul Dzhanabaevna,
candidate of technical science, associate professor,
M. Auezov South Kazakhstan state university
Mamyrbekova Aizhan Kumekbaevna, сandidate of chemical science,
associate professor, A. Yasawi International kazakh-turkish university
Electric conductivity of Cu (NO3)2∙3 Н2О solutions in
dimethylsulfoxide
Abstract: Conductometric method studies electric conductivity of solutions crystalohydrate nitrate of
copper Cu (NO3)2∙3 Н2 О in dimethylsulphoxide (DMSO) within the limits of concentration 0.01–2.82 M
at 288–318 K electrodeposition are calculated limiting molar electrodeposition electrolit, limiting mobility
of ions Cu2+ and NO3-, effective factors of diffusion of ions of copper (II) and nitrate-ions, a degree and a
constant electrolytical dissociation at various temperatures.
Keywords: electrodeposition, dimethylsulphoxide, crystalohydrate of nitrate of copper (II),
conductometry, electrolyte.
The water solution of copper (II) nitrate acidified
by nitric acid is of interest as electrolyte of coppering,
carried out at the raised density (till 100 А∙dm–2).
The received coverings do not contain nonmetallic inclusions and are characterized by low resistance
[1, 64]. For complicating of parallel restoration of
nitrate-ions harmfullyEinfluencing on extraction of
metal it is offered to introduce in nitrate electrolyte
chlorides-ions, various buffer, surface-active and
other additives [2, 50].
In spite of the fact that it is marked in literature
the high solubility of nitrate salts of many metals in
dimethylsulfoxide (DMSO), solubility of anhydrous
copper (II) nitrate in DMSO is not studied.
DMSO is bipolar aprotonic solvent adsorbed
on a surface of metals by positive end, through the
atom of sulphur. In liquid DMSO in usual conditions (lower than 40 °С) molecules of (СН3)2SO
are bonded in dimeric polymers, in which basis fournuclear cycles [3, 380–395].
Taking place weak interaction of hydrogen atoms
of methyl groups with oxygen of the nearest next
molecule complicates occurrence of long molecular bonds. Nevertheless in formed homomolecular
associates round each molecule of DMSO 12 other
28
molecules are coordinated it is established experimentally [4, 3803], it means that in liquid DMSO
units from 13 molecules are the steadiest. The superfluous negative charge of oxygen atom of the
molecule (СН3)2SO causes formation of hydrogen
bond with molecules of Н2О, more stronger, than
with methyl group of molecules DMSO. Formation
of strong Н‑bonds is provedby the analysis of thermodynamic properties of system Н2O-DMSO [5,
2240]. It is offered the following structures of heteromolecular associates (CH3)2SO …H2O (1) and
(CH3)2SO …H2O (2) appearing in binary system
water — DMSO.
Really, from dimethylsulfoxide solution of copper nitrate the qualitative copper coverings are received [6, 1165]. High solubility of copper nitrate
crystallohydrate Cu(NO3)2∙3Н2О in DMSO is established [7, 416].
In work the results of research of
Cu(NO3)2.3Н2О solution electric conductivity in
DMSO in the range of temperatures 288–318 K is
described. Conductivity of solutions was measured
by conductometer ОК‑102/1. Electrodes made
from the platinized platinum are rigidly fixed on the
certain distance. The constant of conductometric
Electric conductivity of Cu (NO3)2∙3 Н2О solutions in dimethylsulfoxide
cells was determined by 0.1 M КCl. The cell with
the studied solution was thermostated with accuracy 0.5 °С by ultrathermostat UTU‑4. Used in work
crystallohydrate was synthesized from a copper
wire and was cleared by recrystallization from a water solution. Chemically pure DMSO was exposed
to vacuum distillation (nD25 = 1.4816).
Electric conductivity of Cu(NO3)2.3Н2О solutions in DMSO quickly increases at temperature
288 K with growth of the salt content in a solution
till 0.4 M. The further increase of copper nitrate trihydrate solution concentration in DMSO leads to
gradual decrease of electric conductivity till some
limiting value. At the raised concentration (above
1.4) reproducibility of measurements decreases.
With increase of temperature till 318 K mobility
of electrolyte ions is accelerated and conductivity of
solutions increases. At 318 K disorder of experiment
points extends in area of lower concentration that is
explained by destruction of the intermolecular hydrogen bonds appearing at low temperatures between molecules (CH3)2SO and H2O, introduced in
structure of crystallohydrate.
Dependence of molar electric conductivity Λ
[1/2Cu (NO3)2.3Н2О, DMSO, Т] of studied solutions from concentration in the diluted solutions
(till 0.5 M) is kept in with the parabolic law of Kolraush-Onzager.
With temperature growth the inclination of line
section increases and simultaneously the disorder of
experimental points strengthens. On values of electric conductivity by a method of Fuoss and Krauss
[8, 125–130] the values of limiting molar electric
conductivity are established and association constants in investigated solutions are calculated. Temperature increase causes decrease of size of relative
temperature coefficient of electric conductivity of
dimethylsulfoxide solution of copper salt εΛº =
(∂lnΛ0/∂T)c. Such dependence of temperature factor of electric conductivity, marked by Valden [9,
602], testifies to viscosity imposing, as essential factor of mobility of ions.
Certain interest has the dependence of relative
temperature factor of electric conductivity of investigated systems from concentration of solution.
In diluted (lower than 0.3 M) solutions of copper
nitrate in DMSO the average size of temperature
factor of electric conductivity with in temperatures
288–308 K of the same order as εΛo is 0.0216 К–1.
And at temperatures 308–318 K it is lower or equal
to 0.0190 К–1. With increase of the content of copper
salt in solution εΛ increases by a curve that is connected with strengthening of interaction of solution
components and aggregation of received products.
Maxima on the diagram of dependence of relative
temperature factor of electric conductivity from
structure indicate the chemical interaction of components, and their abscissas correspond to structure
of connections formed in solution.
The first and second maxima correspond the
following parities of molar share of components
[Cu(NO3)2]: [Н2О]: [(CH3)2SO]=1:3:28 and
1:3:14 accordingly. The existence of steady homomolecular units from 13 molecules (CH3)2SO in
liquid DMSO was mentioned above. From the
received parities it follows that in formed adducts
of the first maximum on mole of crystallohydrate
Cu(NO3)2∙3Н2О it is necessary two associates of
DMSO, in more concentrated solution (0.9 M) one
associate.
Continuing hypothetical, based on ε, C — dependences, in conclusion, it is possible to assume
that in process of increase of copper salt content in
a solution large units on a basis of homomolecular associates of DMSO are decomposed, forming
solvated ions of usual type and heteromolecular
associates of water with DMSO. Solvated ions and
heteromolecular associatesare united with molecules of DMSO in process of increase of solution
concentration. Simultaneously in solution the possibilitiy of ionic association owing to electrostatic
adhesion of cations and anions of electrolyte appears
and strengthens. There is aggregation and agglomeration of particles in solution, causing observed in
experiment increase of temperature factor of conductivity of investigated solutions. Maximum is
more expressed in the diluted solutions (0.47 M)
when homomolecular associates in DMSO prevail.
The maximum is more indistinct at concentration
0.94 M and disappears absolutely in more concentrated solutions when homomolecular associates
are destroyed and the increasing role the products
29
Section 5. Physical chemistry
of interionic interactions and heteromolecular associates play. Increase of temperature factor with
growth of concentration is caused also by increase
of solutions viscosity.
On values of limiting molar electric conductivity
and mobility of ions of NO3– in DMSO λо(NO3–,
DMSO, 298 K) =27.0 S·cm2·mole–1 on the basis
of independence of ions movement of Kolraush the
mobility of copper (ІІ) ions in DMSO are calculated.
Calculations of λо(NO3–) and λо(1/2 Сu2+) at various temperatures are made, accepting temperature
factors of conductivity of ions equal to temperature
factor of conductivity of electrolyte.
In DMSO the mobility of Сu (ІІ) ions is higher
than mobility of NO3– ions. At the same time the
parity of mobility of Сu2 + and NO3– ions in water is
reverse according to the observed one in DMSO. In
water solutions mobility of copper (ІІ) ions is rather
higher than in the organic medium. These phenomena are explained by stronger solvation of copper (ІІ)
ions in DMSO and the raised viscosity of solutions.
In pure DMSO the solvent molecules at
room temperatures form steady enough units
with 13 molecules. Homomolecular associates of
DMSO are linked poorly and consequently the
solvent possesses poor expressed that is broken at
temperatures about 318 K. Small quantity of copper nitrate crystallohydrate dissolving in DMSO,
are dissociated completely. Thus electrolyte components are connected mainly with mentioned
multi-molecular units DMSO, forming complexes of type Cu (DMSO)62+ or [Cu (DMSO)4
(Н2 О)2]2+, and molecules Н2О form stable solvates
Н2О… (Н3 С)2SO. With increase of salt concentration the share of molecules of the solvent on
one ion in solution decreases. Deficiency of mol-
ecules for ions increases because of increase of electrolyte content and molecules of water, being introduced with crystallohydrate. Water molecules
contacting with molecules (Н3 С)2SO by hydrogen
bonds, cause disintegration of homomolecular associates of the organic nature and, forming stronger
heteromolecular associates cause strengthening of
structuring and, as consequence, increase of viscosity of solution. In process of increase of concentration of DMSO decreases solvation number of
Cu2+ and probably, of NO3–. As a result of action
of these two factors solvation of ions decreases
and viscosity of solution increases and at 288 K in
0.4 M solution association of ions of electrolyte
gets appreciable value, preventing the diffusion
of ions and work of conductivity of solution. The
further increase of concentration of electrolyte is
accompanied by increasing of electric conductivity. Increasing of temperature causes the general increase of mobility of ions and conductivity
of solution at the expense of increase of diffusion
speed and migration of ions, and also displacement
of electric conductivity maximum to a higher concentration. At higher temperatures (308–318 K)
the mentioned heteromolecular associates are decomposed and viscosity decreases.
Thus, сrystallohydrate of copper (II) nitrate is
well dissolved in dimethylsulfoxide in a wide interval of concentrations (we test solutions with
concentrations till 2.8 M of Сu (NО3)2·3Н2О) and
temperatures 288–318 K. Electric conductivity of
solutions depending on concentration submits to
known laws. The maximum electric conductivity is
observed in 0.4 M solution of copper (II) nitrate
trihydrate in DMSO at Т=288 K which is displaced
to higher concentration at the raised temperatures.
References:
1. Volodin G. F., Signal L. N., Tyurin Yu. On accelerating the role of nitrate ions in the electrodeposition of
copper.//Proceedings of the universities. Chemistry and Chemical Engineering technology, 1989. – N
32 (11). – Р. 64.
2. Gritsan D. N., Pentsova G. V. The role of the outsider of the anion in the electrodeposition of copper nitrate solutions.//Theory and practice of protection of metals from corrosion. – Kuibyshev, 1985. – Р. 50.
3. Martin D., Hauthal H. Dimethylsulfoxid. – Berlin: Academic-Verlag, 1971. – 494 p.
4. Rao 
B. G., Singh 
U. J.A free energy perturbation study of salvation in methanol and
dimethylsulfoxide.//J. Amer. Chem. Soc. 1990. – Vol.112. – N10. – Р. 3803.
30
Electric conductivity of Cu (NO3)2∙3 Н2О solutions in dimethylsulfoxide
5. Cowie J. M., Toporowski P. M. Association in the binary liquid system dimethylsulphoxide-water.//Can. J. Chem. 1981. – Vol. 39. – N 11. – Р. 2240.
6. Vahidov R. S. Electrodeposition of copper from the non-aqueous solutions.//Elektrohimiya, 1994. –
Vol. 30. – N 97. – Р.1165–1166.
7. Mamyrbekova A. K. Concentration dependences of the density, viscosity and refraction in dex of Cu
(NO3)2.3H2O solutions in DMSO AT 298 K.//Russian Journal of Physical Chemistry, 2013. – Vol.87. –
N 3. – Р. 414–417.
8. Izmailov N. A. Electrochemistry solutions. – M.: Chemistry, 1986. – 153 p.
9. Gordon J. Organic chemistry of electrolyte solutions. – M.: Mir, 1979. – 712 p.
31