GOST 12560.1-78
GOST 12560.1−78 Alloys palladium-silver-cobalt. Method for the determination of cobalt and silver (with Change No. 1)
GOST 12560.1−78
Group B59
STATE STANDARD OF THE USSR
ALLOYS PALLADIUM-SILVER-COBALT
Method for the determination of cobalt and silver
Palladium-silver-cobalt. Method of the determination of cobalt and silver
AXTU 1709*
______________
* Introduced advanced Edit. N 1.
Valid from 01.07.1979
prior to 01.07.1984*
_________________________________
* Expiration removed by Protocol No. 3−93
The interstate Council for standardization,
Metrology and certification (ICS No. 5/6, 1993). -
Note the manufacturer’s database.
DEVELOPED by Sverdlovsk factory on processing of nonferrous metals
GL. engineer A. A. Kuranov
Heads: G. S. Haak, V. T. Levin, V. D. Ponomareva
Contractor R. M. Bogdanova
INTRODUCED by the Ministry of nonferrous metallurgy of the USSR
Member Of The Board Of A. P. Snurnikov
The draft all-Union scientific research Institute of standardization (VNIIS)
Director A. V. Gichev
APPROVED AND promulgated by the Decree of the State Committee of standards of Ministerial Council of the USSR of March 24, 1978 N 794
REPLACE GOST 12560−67 in part of sec. 2 and 3
The Change N 1, approved and put into effect by the Decree of the USSR State Committee for standards from
Change No. 1 made by the manufacturer of the database in the text IUS N 2, 1989
This standard specifies the method of chelatometric determination of cobalt (at a mass fraction of cobalt from 4.5 to 5.5%), potentiometric method for determination of silver (at a mass fraction of silver from of 34.4 to 35.6%) with the use of automatic titration unit in a palladium-silver-cobalt alloys.
The method is based on titration of cobalt with a solution of Trilon B in the presence of murexide as an indicator, followed by potentiometric titration of silver in ammonia environment with a solution of potassium iodide to a predetermined value of the potential difference. As reference electrode in potentiometric titration is used Hartley electrode, the indicator electrode is a silver wire.
1. GENERAL REQUIREMENTS
1.1. General requirements for method of analysis according to GOST 22864−83.
(Changed edition, Rev. N 1).
1.2. The numerical value of the result of the analysis must end with the digit the same category, and permissible differences.
(Added, Rev. N 1).
2. APPARATUS, REAGENTS AND SOLUTIONS
Laboratory scales lever according to GOST 24104−88*.
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* On the territory of the Russian Federation GOST 24104−2001. — Note the manufacturer’s database.
pH meter laboratory pH-340.
Magnetic stirrer MM-2.
The block automatic titration lab BAT-12-LM.
Burette with automatic zero setting capacity of 50 cm.
Pipettes according to GOST 20292−74* with a capacity of 25 cm.
________________
* On the territory of the Russian Federation there are 29169−91 GOST, GOST 29227−91−29229−91 GOST, GOST 29251−91-GOST 29253−91. — Note the manufacturer’s database.
The glasses according to GOST 25336−82, with a capacity of 150 cm.
Silver brand 999,9 according to GOST 6836−80*.
________________
* On the territory of the Russian Federation GOST 6836−2002. — Note the manufacturer’s database.
Nitric acid GOST 4461−77 diluted 1:1.
Ammonia water according to GOST 3760−79.
Cobalt grade K0 GOST 123−78*.
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* On the territory of the Russian Federation GOST 123−2008. — Note the manufacturer’s database.
Standard solution of cobalt; prepared as follows: 0,5000 g of cobalt is dissolved by heating in 20 cmof nitric acid, diluted 1:1, boil to remove oxides of nitrogen, cooled, transferred to a volumetric flask with a capacity of 500 cm
, made up to the mark with water and mix.
1 cmof the solution contains 0.001 g of cobalt.
Murexide, a freshly prepared solution with a mass fraction of 0.3%; prepared as follows: 0.03 g of indicator was dissolved with heating in 10 cmof water.
Sodium acetate according to GOST 199−78, a solution with a mass fraction of 20%.
Ammonium acetate according to GOST 3117−78, a solution with a mass fraction of 20%.
Ammonium acetate buffer solution; prepared as follows: five volumes of a solution with a mass fraction of 20% ammonium acetate and neutralized with ammonia until the litmus рН7, mixed with one volume of solution with a mass fraction of 20% sodium acetate and at every 100 cmof this mixture, add 3 cm
of ammonia solution.
Salt is the disodium Ethylenediamine-N, N, N', N'-tetraoxane acid, 2-water (Trilon B) according to GOST 10652−73, 0.025 M solution; prepared as follows: 9.3 g Trilon B dissolved in 500 cmof water when heated, transferred to a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and mix.
Determination of the mass concentration of 0.025 M solution of Trilon B
25 cmstandard solution of cobalt was placed in a conical flask with a capacity of 250 cm
, is diluted with 25 cm
of water, neutralized with ammonia to a faint smell, injected 10 cm
of ammonium acetate buffer solution, five drops of a solution of murexide and titrated 0,025 m solution of Trilon B to switch the orange color of the solution in raspberry.
The mass concentration of the solution Trilon B (), expressed in g/cm
of cobalt, calculated as follows:
where is the mass of cobalt, taken for titration, g;
— volume of solution Trilon B, spent on titration, sm
.
The anhydrous sodium carbonate according to GOST 83−79.
Potassium iodide according to GOST 4232−74, 0.06 M solution; prepared as follows: 9.6 g of potassium iodide dissolved in 500 cmof water is added 1.06 g of sodium carbonate, transferred to a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and mix.
Determination of the mass concentration of 0.06 M solution of potassium iodide
A portion of silver with a mass of 0.18−0.20 g, weighed with accuracy of more than 0.0001 g, placed in a beaker with a capacity of 150 cm, is dissolved by heating in 10 cm
of nitric acid, diluted 1:1, heated to remove oxides of nitrogen, dilute with water to 30−50 cm
and neutralized with ammonia to a faint smell. The solution was titrated as described in sec. 4.
The mass concentration of a solution of potassium iodide (), expressed in g/cm
of silver, calculated by the formula
where — weight of silver, g;
— the volume of potassium iodide solution consumed for titration, sm
.
(Changed edition, Rev. N 1).
3. PREPARATION FOR ASSAY
3.1. A sample of alloy weighing 0.5 g were placed in a glass with a capacity of 150 cmand dissolved by heating in 50 cm
of nitric acid, diluted 1:1. The solution was evaporated to 10 cm
, is diluted with 25 cm
of water and neutralized with ammonia until the formation of a complex of palladium and cobalt. The solution should have a faint smell of ammonia, with excess of ammonia are added dropwise nitric acid, and in the case of an excess of nitric acid is added drop by drop ammonia.
(Changed edition, Rev. N 1).
4. ANALYSIS
4.1. Definition of cobalt
Prepared for the analysis of the solution add 10 cmof ammonium acetate buffer solution, 4−5 drops of a solution of murexide and titrated with 0.05 n solution of Trilon B to switch the orange color of the solution in the crimson, after which the solution determine the content of silver.
(Changed edition, Rev. N 1).
4.2. Determination of silver
Included in the network of power instrument pH 340, BAT-12-LM and MM-2. After heating for 30 minutes check and adjust the zero control unit BAT-12-LM, which set the switch «Kind of» instrument pH 340 in position «+MV» switch «Swipe» at 1500 mV setpoint «Pulse flow» of the BAT-12-LM to a value of «0.2» and the rotating axis of the potentiometer «Set. zero», achieve a situation in which the signal light «Titration» lights up or starts flashing. Then, the rotating axis of the potentiometer «Set. zero» in the opposite direction, to achieve a situation in which the signal light «Titration» is completely off.
Set on the knobs of the device BAT-12-LM: the «target point» — the value «7» and precisely «to 0.3», which corresponds to 750 mV, the «Pulse flow» — a zone of proportionality «2,0», «exposure Time» — 10.
Attach the electrodes to the instrument pH 340. The reference electrode (Hartley) attached in the terminal «VSP», the indicator electrode (silver wire) to terminal «ISM».
In the analyzed solution after the determination of cobalt lower the stirring rod and set beaker with the solution on the stirrer.
Immersed in the solution electrodes and the metering tube, which should be located close to the indicator electrode to avoid perelitsovyvat solution.
Switch the magnetic stirrer set at division 2 and at the end of the titration — division «4».
The addition of ammonia or nitric acid into the solution set the arrow of the instrument pH 340 to 1000 mV (if the arrow points to more than 1000 mV, ammonia is added).
Fill the burette a 0.06 n solution of potassium iodide and set the tap to a position at which the solution from the burette will flow.
Set the switch «works» of the BAT-12-LM to the «Titration down», when this warning light illuminates «Titration» and start a flow of 0.06 N. the solution of potassium iodide in a glass.
After the end of titration the indicator light «End of titration» and stops the supply of a 0.06 n solution of potassium iodide.
Then set the switch the magnetic stirrer on the zero division, the switch «works» of the BAT-12-LM in the «Manual» position. Next, remove the electrodes from the solution, raising the electrode holder in the upper position, and wash them with water.
The glass is removed from the magnetic stirrer is removed from the solution stirring rod and wash it with water.
5. PROCESSING OF THE RESULTS
5.1. Mass fraction of cobalt () in percent is calculated by the formula
where — volume of 0.05 n solution of Trilon B, used for titration, cm
;
— mass concentration of the solution Trilon B on the cobalt, g/sm
;
— the mass of alloy,
5.2. Mass fraction of silver () in percent is calculated by the formula
where — volume of 0.06 n potassium iodide solution consumed for titration, cm
;
— mass concentration of a solution of potassium iodide on silver, g/cm
;
— the mass of alloy,
5.3. The difference between the largest and smallest results of the three parallel measurements at a confidence probability of 0.95 does not exceed the absolute value of the admitted discrepancy
of 0.15%.
The difference between the two results of the analysis of the same sample obtained in different laboratories, should not exceed the absolute value of the admitted discrepancies of 0.25%.
5.1−5.3. (Changed edition, Rev. N 1).
5.4. Control of the correctness of the results of determining the mass fraction of cobalt and silver is held by the reproduction of their mass fraction in the artificial mixtures the chemical composition close to the composition of the analyzed alloy, drawn through the entire course of the analysis.
The sample analysis results are considered correct if the absolute difference between the maximum and minimum values of the mass fraction of cobalt and silver in the artificial mixture does not exceed 0.12%.
(Added, Rev. N 1).
