GOST 3240.17-76
GOST 3240.17−76 magnesium Alloys. Methods for determination of silver (with Change No. 1)
GOST 3240.17−76
Group B59
INTERSTATE STANDARD
MAGNESIUM ALLOYS
Methods for determination of silver
Magnesium alloys.
Methods for determination of silver
ISS 77.120.20
AXTU 1709
Date of introduction 1978−01−01
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of aviation industry of the USSR
2. APPROVED AND promulgated by the Decree of the State Committee of standards of Ministerial Council of the USSR from
3. INTRODUCED FOR THE FIRST TIME
4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
Item number |
| GOST 1277−75 |
2.2, 3.2 |
| GOST 3240.0−76 |
1.1 |
| GOST 4233−77 |
2.2 |
| GOST 4461−77 |
2.2 |
| GOST 4517−87 |
3.2 |
| GOST 5457−75 |
3.2 |
| GOST 11125−84 |
3.2 |
| GOST 25086−87 |
2.5 |
| GOST 27067−86 |
2.2 |
| THAT 6−09−5359−87 |
2.2 |
5. Limitation of actions taken by Protocol No. 2−92 of the Interstate Council for standardization, Metrology and certification (ICS 2−93)
6. EDITION with Change No. 1, approved in June 1987 (IUS 11−87)
This standard specifies the titrimetric and atomic absorption methods for the determination of silver (at a mass fraction of silver from 0.5 to 2%).
1. GENERAL REQUIREMENTS
1.1. General requirements for methods of analysis GOST 3240.0.
2. TITRIMETRIC METHOD FOR DETERMINATION OF SILVER CONTENT
2.1. The essence of the method
The method is based on the formation of silver thiocyanate ammonium sparingly soluble salt white. The first superfluous drop of the thiocyanate solution ammonium reacts with salesonline with alum, forming a iron thiocyanate red color.
2.2. Reagents and solutions
Nitric acid according to GOST 4461, diluted 1:1, 1:6.
Silver nitrate according to GOST 1277.
Sodium chloride according to GOST 4233.
A standard solution of silver, prepared as follows: 3,146 g pre-dried in a drying Cabinet at 150 °C to constant weight of silver nitrate dissolved in bidistilled water, is introduced 1 cmof nitric acid, transferred to a volumetric flask with a capacity of 100 cm
, is diluted with bidistilled water to the mark and mix thoroughly.
1 cmof solution contains 2.0 mg of silver.
Salesonline alum on the other 6−09−5359−87 solution; prepared as follows: 3 g gentoomaniac alum and 2 cmof sulphuric acid are dissolved in 100 cm
of water.
Ammonium thiocyanate GOST 27067, 0.02 M solution; prepared as follows: to 1.52 g of ammonium thiocyanate are dissolved in 1000 cmof water. The titer of a solution of ammonium thiocyanate is determined by silver nitrate.
This 25 cmof silver nitrate is placed in a conical flask with a capacity of 250 cm
, add 5 cm
3% gentoomaniac alum solution, and titrated with a solution of ammonium thiocyanate until the beginning of discoloration (pale red).
The titer of a solution of ammonium thiocyanate (a), expressed in g/cm
of silver, calculated by the formula
where — the amount of silver nitrate, taken for titration, g;
the amount of ammonium thiocyanate consumed for titration, sm
.
2.3. Analysis
A sample of alloy weighing 2 g was dissolved in a conical flask with a capacity of 250 cm, flow 10 cm
of nitric acid, diluted 1:6 in 40 cm
of nitric acid, diluted 1:1 chlorine-free, boil to remove oxides of nitrogen, and then the wall of the flask is washed with water, cool, add 5 cm
of gentoomaniac alum solution, and titrated with 0.02 M solution of ammonium thiocyanate until the beginning of discoloration (pale red). The solution is strongly shaken, and, if the colour disappears, add another drop of the titrated solution of ammonium thiocyanate until a stable coloring.
2.2; 2.3. (Changed edition, Rev. N 1).
2.4. Processing of the results
2.4.1. Mass fraction of silver () in percent is calculated by the formula
where — the amount of 0.02 n solution ammonium thiocyanate, spent on titration, sm
;
— weight alloy, g;
the titer of a solution of ammonium thiocyanate, expressed in g/cm
of silver.
2.4.2. Allowable absolute differences of the results of the parallel definitions should not exceed the values given in table.1.
Table 1
| Mass fraction of silver, % |
The absolute allowable difference, % |
| To 0.5 |
0,05 |
| SV. 0.5 to 1.0 |
0,1 |
| «1,0» 2,0 |
0,2 |
2.5. Control of measurement accuracy
Control the accuracy of measuring the mass fraction of silver from 0.5 to 2% is carried out by additives in accordance with GOST 25086.
(Added, Rev. N 1).
3. ATOMIC ABSORPTION METHOD FOR DETERMINATION OF SILVER CONTENT
3.1. The essence of the method
The method is based on measuring the atomic absorption of silver at the wavelength of 328.8 nm in the flame acetylene-air.
3.2. Apparatus, reagents and solutions
Spectrophotometer atomic absorption.
Bidistilled water, checked for absence of chlorine ions, obtained according to GOST 4517.
Dilution of all solutions is carried out only with bidistilled water.
Silver nitrate according to GOST 1277, H. h. or h.d. a.
Nitric acid according to GOST 11125, OS.CH., does not contain chlorine ions.
Standard solutions of silver nitrate.
Solution A, prepared as follows: 1,5730 g pre-dried in a drying Cabinet at 150 °C to constant weight of silver nitrate dissolved in bidistilled water, is introduced 1 cmof nitric acid, transferred into a measuring flask with volume capacity of 1000 cm
, is diluted to the mark with water and mix thoroughly.
1 cmof the solution contains 1 mg of silver.
Solution B is prepared as follows: 50 cmsolution And taken in a flask with a capacity of 50 cm
, is diluted to the mark with water and mix.
1 cmof a solution contains 0.1 mg of silver.
Acetylene in cylinders GOST 5457
.
3.1; 3.2. (Changed edition, Rev. N 1).
3.3. Analysis
3.3.1. 0.1 g sample was placed in a conical flask of resistant glass with a capacity of 100 cm, pre-washed with nitric acid and double-distilled water until negative reaction on chlorine-ion. Then washed with two portions of double-distilled water at 20 cm
each, dissolved in 10 cm
of nitric acid under low heat on the stove, closing after adding nitric acid to the flask with a watch glass to avoid evaporation of nitric acid. Upon completion of the dissolution solution is transferred to a volumetric flask with a capacity of 100 cm
. The bulb, which conducted the dilution, rinse the 25 cm
double-distilled water and the washings are attached to the main solution. The resulting mixture was cooled, diluted with bidistilled water to the mark, mixed and injected into the atomizer of the spectrophotometer.
The value of optical density of flame lay on the calibration chart. In order to avoid errors in unstable operation of the device after every four samples to check the slope of the calibration curve re-photoretrieval one of the previously analyzed solutions. When you change the optical density by more than 2% the analysis of the last four samples is repeated.
3.3.2. Construction of calibration curve
In seven volumetric flasks with a capacity of 100 cmis administered at 10 cm
of nitric acid; 0; 5,0; 10,0; 15,0; 20,0; 25,0 and 30 cm
of solution B, which corresponds to: 0; 0,05; 0,10; 0,15; 0,20; 0,25 and 0.30 mg of silver. The solutions were diluted to the mark with water, mix, photometric as specified in claim 3.3.1, and build a calibration curve.
3.3.1;
3.4. Processing of the results
3.4.1. Mass fraction of silver () in percent is calculated by the formula
where is the mass of silver was found in the calibration schedule,
— the weight of the portion of alloy,
3.4.2. Allowable absolute differences of the results of the parallel definitions should not exceed the values given in table.2.
Table 2
| Mass fraction of silver, % |
The absolute allowable difference, % |
| From 0.5 to 1.0 |
0,05 |
| SV. 1,0 «2,0 |
0,1 |
3.4.1;
3.5. Control of measurement accuracy
Control of measurement accuracy according to claim
(Added, Rev. N 1).
