GOST 3240.19-76
GOST 3240.19−76 magnesium Alloys. Method for the determination of chlorine (with Change No. 1)
GOST 3240.19−76
Group B59
INTERSTATE STANDARD
MAGNESIUM ALLOYS
Method of determination of chlorine
Magnesium alloys.
Method for determination of chlorine
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 |
Section number, paragraph |
| GOST 1277−75 |
Sec. 2 |
| GOST 3240.0−76 |
1.1 |
| GOST 4204−77 |
Sec. 2 |
| GOST 4233−77 |
Sec. 2 |
| GOST 4461−77 |
Sec. 2 |
| GOST 4523−77 |
Sec. 2 |
| GOST 25086−87 |
Sec. 4 |
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 turbidimetric method for the determination of chlorine (if chlorine mass fraction from 0.002 to 0.01%).
The method is based on formation of fine-dispersed Sol of silver chloride with the interaction of chloride ions with silver nitrate solution. The concentration of chlorine ion measured by the reduction in the intensity of transmitted light at a wavelength of 400 nm. Determination of chloride ions prevents undissolved zirconium, which is separated by centrifugation.
1. GENERAL REQUIREMENTS
1.1. General requirements for method of analysis according to GOST 3240.0.
2. APPARATUS, REAGENTS AND SOLUTIONS
Type photoelectrocolorimeter FEK-56, or FEK 60.
Sulfuric acid according to GOST 4204, approximately 25% solution by mass is prepared as follows: 37 cmof concentrated acid diluted with water to 100 cm
.
Nitric acid according to GOST 4461, diluted 1:1.
Magnesium sulfate according to GOST 4523, free from chlorides; prepared as follows: 250 g of magnesium sulfate (MgSO·7H
O) is dissolved in 600−700 cm
of water is added 110 cm
1% solution of silver nitrate and 50 cm
of nitric acid, diluted 1:1, heated to (50±5) °C and allowed to settle during the day. The solution is filtered through a dense filter, washed with water, collecting it in a measuring flask with volume capacity of 1000 cm
, made up to the mark with water and mix. The solution should be transparent.
Silver nitrate according to GOST 1277, 2% solution.
Sodium chloride according to GOST 4233.
The standard solutions of chlorine
Solution a: 1,649 g of sodium chloride, dried to constant mass at 500 °C, dissolved in water, transferred to a volumetric flask with a capacity of 1 DM, made up to the mark with water and mix.
1 cmof the solution contains 1 mg of chlorine.
Solution B: 10 cmsolution And transferred to a volumetric flask with a capacity of 500 cm
and topped to the mark with water.
1 cmof the solution contains 0.02 mg of chlorine.
Centrifuge.
(Changed edition, Rev. N 1).
3. ANALYSIS
3.1. A sample of alloy weighing 1 g is placed in a beaker with a capacity of 100 cm, flow 10 cm
of water and 20 cm
of sulphuric acid portions of 1−2 cm
until dissolved. After dissolution of the alloy solution is transferred into a volumetric flask with a capacity of 50 cm
, made up to the mark with water and mix. (If a precipitate insoluble in sulfuric acid zirconium solution is placed in a test tube and tsentrifugirujut. The solution was decanted into a volumetric flask with a capacity of 50 cm
, the tube is rinsed with not more than 3 cm
of water, tsentrifugirujut, attached to the main solution). In volumetric flasks add 2cm
of a solution of silver nitrate and left in dark place for 15 min. the solution was Then topped to the mark with water, mix and measure optical density of solution on a photoelectrocolorimeter with a blue filter (wavelength 400 nm) in a cuvette with a layer thickness of 50 mm. at the same time spend control experience.
In a volumetric flask with a capacity of 50 cmpour 20 cm
of a 25% solution of sulfuric acid, is then carried out through all stages of the analysis. Solution comparison is the solution of the reference experiment.
Mass fraction of chlorine found by the calibration graph
the IR.
3.2. Construction of calibration curve
In a series of volumetric flasks with a capacity of 50 cmpoured from microburette standard solution B in an amount of 0; 0,5; 1,0; 1,5; 2,0; 2,5; 3,0; 4,0; 5,0 and 6.0 cm
, which corresponds to: 0; 1·10
; 2·10
; 3·10
; 4·10
; 5·10
; 6·10
; 8·10
; 1·10
and 1.2·10
g of chlorine. Poured all the flasks for 16 cm
solution of magnesium sulfate, and purified from chlorine, 2 cm
of a solution of silver nitrate, leave for 15 min in a dark place and then diluted to the mark with water and measure the optical density as indicated in paragraph 3.1. Solution comparison is the solution of the reference experiment. According to the obtained values of optical densities and corresponding chlorine concentrations to build calibration
schedule.
3.1; 3.2. (Changed edition, Rev. N 1).
3.3. Processing of the results
3.3.1. Mass fraction of chlorine (the) percentage is calculated by the formula
where is the mass of chlorine was found in the calibration schedule g;
— the weight of the portion of the alloy taken for photometry,
(Changed edition, Rev. N 1).
3.3.2. Allowable absolute differences between the results of the parallel definitions should not exceed the values given in the table.
| Mass fraction of chlorine, % |
The absolute allowable difference, % |
| From 0.002 to 0.005 |
0,001 |
| SV. 0,005 «0,01 |
0,002 |
4. CONTROL OF MEASUREMENT ACCURACY
Accuracy control measurement of chlorine mass fraction from 0.002 to 0.01% is carried out by additives in accordance with GOST 25086.
Sec. 4. (Added, Rev. N 1).
