Solubility of Silver Bromate in Aqueous Solutions of Manganese, Cobalt, Nickel, and Copper Nitrates and Sulfates
Abstract Generated abstract
The study examines how aqueous nitrates and sulfates of manganese, cobalt, nickel, and copper affect the solubility behavior of silver bromate at 25°C over electrolyte concentrations from 0.001 to 1 mol/l. Using gravimetric and iodometric determinations, the authors measured silver bromate solubility and calculated corresponding solubility products and activity coefficients, comparing the results with earlier data for zinc and cadmium salts. In all systems, increasing electrolyte concentration increased solubility and solubility product while decreasing the activity coefficient, with only small differences among the studied transition metal salts and a somewhat stronger effect from sulfates than nitrates. The work provides concentration-dependent ranges and a practical relation for estimating silver bromate solubility in these electrolyte solutions from activity coefficients.
Full Text
SOLUBILITY OF SILVER BROMATE IN AQUEOUS SOLUTIONS OF NITRATES AND SULFATES OF MANGANESE, COBALT, NICKEL, AND COPPER
Yu. L. Lel’chuk, B. B. Sokolovich, L. L. Skriptova,
Kh. A. Lel’chuk, O. V. Chashchina
(Presented by Professor A. G. Stromberg, Doctor of Chemical Sciences)
In studying the solubility of a silver bromate precipitate in aqueous solutions of nitrates and sulfates of many metals of the main subgroups of D. I. Mendeleev’s periodic system of elements, we have established that the solubility of this precipitate, its solubility product, and the activity coefficient depend not only on the valence type of the external electrolyte and on the ionic strength of the liquid phase in which precipitation is carried out, but also on the chemical nature of the corresponding electrolytes, on the position in the periodic system of the metal from which the salt is formed, and on the anion with which it is associated [1].
Nitrates and sulfates of metals of one and the same group of the periodic system of elements increase the solubility and the solubility product of the precipitate, and decrease the activity coefficient, to a greater extent the greater the atomic weight, the atomic number of the metal in the periodic system, and the effective radius of its cation [2].
Salts of metals of one and the same period of the periodic system, at equal normality of the solutions, with increasing atomic number of the metal, decrease their influence on the solubility, the solubility product, and the activity coefficient of silver bromate [3]. Of the two anions studied by us, the sulfate anion has a greater influence on the solubility of the precipitate than the nitrate anion [4].
The present communication is devoted to a study of the influence of nitrates and sulfates of manganese, cobalt, nickel, and copper on the properties of the silver bromate precipitate.
Experimental Part
The method of investigation, the preparation of chemically pure silver bromate, and the general scheme of calculations have been described by us earlier [5]. All aqueous solutions of electrolytes were obtained by appropriate dilution of centimolar solutions of chemically pure \( \mathrm{Mn(NO_3)_2 \cdot 6H_2O} \), \( \mathrm{MnSO_4 \cdot 5H_2O} \), \( \mathrm{Co(NO_3)_2 \cdot 6H_2O} \), \( \mathrm{CoSO_4 \cdot 7H_2O} \), \( \mathrm{Ni(NO_3)_2 \cdot 6H_2O} \), \( \mathrm{NiSO_4 \cdot 7H_2O} \), \( \mathrm{Cu(NO_3)_2 \cdot 3H_2O} \), and \( \mathrm{CuSO_4 \cdot 5H_2O} \) with bidistillate. For each concentration of the corresponding electrolyte, two parallel ...
samples. Thus, the data in the tables on the solubility of the silver bromate precipitate in these systems are the mean values of no fewer than four parallel determinations. Silver was determined gravimetrically as AgCl, and the bromate ion iodometrically. The concentrations of the initial electrolyte solutions were determined as follows: manganese nitrate and sulfate—by the gravimetric method as manganese pyrophosphate; cobalt nitrate and sulfate—by the gravimetric nitrite method as potassium hexanitritocobaltate; nickel nitrate and sulfate—by the gravimetric method as nickel dimethylglyoximate; copper nitrate and sulfate—by a volumetric iodometric method in the presence of potassium rhodanide [6]. The precipitate of potassium hexanitritocobaltate was filtered through a glass crucible with a porous bottom No. 4, washed with water acidified with acetic acid, and dried to constant weight at 110°C. Nickel dimethylglyoximate was precipitated from weakly ammoniacal solutions. The precipitate was filtered through a glass crucible with a porous bottom No. 3 and dried at 120°C.
The experimental data obtained are given in Tables 1–3.
Table 1
Solubility of silver bromate in solutions of nitrates and sulfates of manganese, cobalt, nickel, copper, zinc, and cadmium
| Electrolyte | Solubility of silver bromate in 0.001 M solution | Solubility of silver bromate in 0.010 M solution | Solubility of silver bromate in 0.100 M solution | Solubility of silver bromate in 0.300 M solution | Solubility of silver bromate in 1 M solution |
|---|---|---|---|---|---|
| Mn(NO₃)₂ | 8.06·10⁻³ | 8.79·10⁻³ | 1.04·10⁻² | 1.31·10⁻² | 1.71·10⁻² |
| MnSO₄ | 8.28·10⁻³ | 9.18·10⁻³ | 1.15·10⁻² | 1.34·10⁻² | 1.75·10⁻² |
| Co(NO₃)₂ | 7.94·10⁻³ | 8.62·10⁻³ | 1.09·10⁻² | 1.31·10⁻² | 1.67·10⁻² |
| CoSO₄ | 7.99·10⁻³ | 8.81·10⁻³ | 1.12·10⁻² | 1.36·10⁻² | 1.70·10⁻² |
| Ni(NO₃)₂ | 8.44·10⁻³ | 8.74·10⁻³ | 1.11·10⁻² | 1.28·10⁻² | 1.71·10⁻² |
| NiSO₄ | 8.47·10⁻³ | 9.44·10⁻³ | 1.15·10⁻² | 1.40·10⁻² | 1.74·10⁻² |
| Cu(NO₃)₂ | 8.16·10⁻³ | 8.93·10⁻³ | 1.11·10⁻² | 1.30·10⁻² | 1.73·10⁻² |
| CuSO₄ | 8.32·10⁻³ | 9.07·10⁻³ | 1.15·10⁻² | 1.35·10⁻² | 1.74·10⁻² |
| Zn(NO₃)₂ | 8.43·10⁻³ | 9.12·10⁻³ | 1.16·10⁻² | 1.47·10⁻² | 1.93·10⁻² |
| ZnSO₄ | 8.22·10⁻³ | 8.88·10⁻³ | 1.13·10⁻² | 1.40·10⁻² | 1.75·10⁻² |
| Cd(NO₃)₂ | 8.13·10⁻³ | 8.75·10⁻³ | 1.04·10⁻² | 1.32·10⁻² | 1.74·10⁻² |
| CdSO₄ | 8.17·10⁻³ | 8.85·10⁻³ | 1.08·10⁻² | 1.33·10⁻² | 1.72·10⁻² |
Discussion of Results
The behavior of the silver bromate precipitate in all these systems is approximately the same: with increasing electrolyte concentration there is a regular increase in the solubility and in the solubility product of the precipitate, and a decrease in its activity coefficient. The quantitative influence of all the nitrates and sulfates considered here differs little from one another. The greatest increase in solubility is produced by copper nitrate and sulfate, and the smallest by cobalt nitrate and sulfate. In one-molar solutions of these electrolytes the solubility of the precipitate increases, compared with water, by a factor of 2.02–2.14, and the solubility product by a factor of 4.10–4.56. The activity coefficient of AgBrO₃ decreases to 0.419–0.444. As in the systems previously studied by us [2], at the same normality of solutions the sulfate anion gives a somewhat greater increase in the solubility of the precipitate than the nitrate anion. However, the difference in solubility here is small. Comparison of these data with data-
Table 2
Activity coefficient of silver bromate in solutions of nitrates and sulfates of manganese, cobalt, nickel, copper, zinc, and cadmium
| Electrolyte | Average value of the activity coefficient in 0.001 M solution | Average value of the activity coefficient in 0.010 M solution | Average value of the activity coefficient in 0.100 M solution | Average value of the activity coefficient in 0.300 M solution | Average value of the activity coefficient in 1 M solution |
|---|---|---|---|---|---|
| Mn(NO₃)₂ | 0,894 | 0,821 | 0,641 | 0,536 | 0,434 |
| MnSO₄ | 0,889 | 0,805 | 0,617 | 0,515 | 0,421 |
| Co(NO₃)₂ | 0,895 | 0,822 | 0,645 | 0,543 | 0,444 |
| CoSO₄ | 0,890 | 0,807 | 0,624 | 0,526 | 0,436 |
| Ni(NO₃)₂ | 0,892 | 0,821 | 0,641 | 0,536 | 0,434 |
| NiSO₄ | 0,888 | 0,805 | 0,619 | 0,519 | 0,426 |
| Cu(NO₃)₂ | 0,893 | 0,821 | 0,638 | 0,532 | 0,429 |
| CuSO₄ | 0,889 | 0,804 | 0,616 | 0,514 | 0,419 |
| Zn(NO₃)₂ | 0,890 | 0,815 | 0,619 | 0,502 | 0,384 |
| ZnSO₄ | 0,889 | 0,806 | 0,618 | 0,517 | 0,424 |
| Cd(NO₃)₂ | 0,892 | 0,820 | 0,637 | 0,530 | 0,426 |
| CdSO₄ | 0,889 | 0,806 | 0,621 | 0,523 | 0,431 |
Table 3
Behavior of the silver bromate precipitate in molar electrolyte solutions
| Electrolyte | \(C_{\mathrm{AgBrO_3}}\cdot 10^2\) | \(Li' : Li\)¹) | \(Lp' : Lp\)²) |
|---|---|---|---|
| Mn(NO₃)₂ | 1,71 | 2,072 | 4,300 |
| MnSO₄ | 1,76 | 2,133 | 4,556 |
| Co(NO₃)₂ | 1,67 | 2,024 | 4,103 |
| CoSO₄ | 1,70 | 2,061 | 4,250 |
| Ni(NO₃)₂ | 1,71 | 2,072 | 4,294 |
| NiSO₄ | 1,74 | 2,109 | 4,456 |
| Cu(NO₃)₂ | 1,73 | 2,097 | 4,402 |
| CuSO₄ | 1,77 | 2,145 | 4,607 |
| Zn(NO₃)₂ | 1,93 | 2,339 | 5,471 |
| ZnSO₄ | 1,75 | 2,121 | 4,503 |
| Cd(NO₃)₂ | 1,74 | 2,109 | 4,456 |
| CdSO₄ | 1,72 | 2,085 | 4,353 |
with those obtained by us earlier for the nitrates and sulfates of zinc and cadmium [7], shows that, of all the salts of the metals of the side subgroups of the periodic system of elements studied by us, zinc nitrate has the greatest effect on the solubility of the precipitate. In a one-molar solution of zinc nitrate the solubility of AgBrO₃ reaches \(1{,}93\cdot 10^{-2}\), whereas in a solution of zinc sulfate it remains approximately the same as in solutions of the sulfates of manganese, cobalt, nickel, and copper, and is equal to \(1{,}75\cdot 10^{-2}\).
¹) \(Li' : Li\)—the solubility of silver bromate, respectively, in a one-molar electrolyte solution and in water.
²) \(Lp' : Lp\)—the solubility product of silver bromate, respectively, in a one-molar electrolyte solution and in water.
The closeness of the values of the activity coefficient of silver bromate in solutions of nitrates and sulfates of manganese, cobalt, nickel, copper, and cadmium, as well as zinc sulfate (Table 2), makes it possible to determine the solubility of this precipitate in solutions of these electrolytes at any of their concentrations in the interval from 0.001 to 1 mole/l by the formula
\[ C_{\mathrm{AgBrO_3}}=\sqrt{\frac{L_0}{\gamma^2}}, \]
where \(L_0\) is the activity product of the precipitate \(\mathrm{AgBrO_3}=5.50\cdot10^{-5}\); \(\gamma\) is the mean value of the activity coefficient of \(\mathrm{AgBrO_3}\) at the given electrolyte concentration, determined from the curve in Fig. 1.
Fig. 1. Mean value of the activity coefficient of \(\mathrm{AgBrO_3}\) in solutions of nitrates and sulfates of Mn, Co, Ni, Cu, and Cd.
Conclusions
The solubility of a silver bromate precipitate in aqueous solutions of nitrates and sulfates of manganese, cobalt, nickel, and copper was investigated at concentrations of the latter from 0.001 to 1 mole/l at 25°C. The data for these systems were compared with previously obtained data for nitrates and sulfates of zinc and cadmium.
The ranges of change in solubility, solubility product, and activity coefficient of silver bromate as a function of the ionic strength of solutions of nitrates and sulfates of these metals have been shown.
LITERATURE
- Let’chuk Yu. L. Doklady 7th Scientific Conf., TPI, issue 2, 138, 1957.
- Let’chuk Yu. L. Zh. neorg. khimii, 3, 2453, 1958.
- Let’chuk Yu. L. Izv. TPI, 77, 104—112, 1953.
- Let’chuk Yu. L. Izv. TPI, 102, 108, 1959.
- Tananaev I. V., Let’chuk Yu. L., Petrovitskaya B. A. Zh. obshch. khimii, 19, 1207, 1949.
- Knipovich Yu. N., Morachevskii Yu. V. Analysis of mineral raw material, GNTI, Khim. lit., 357, 412, 424, 463, 1956.
- Let’chuk Yu. L. Zh. obshch. khimii, 25, 1273, 1955.