GOST 18904.1-89
GOST 18904.1−89 Tantalum and its oxide. The photometric method for the determination of molybdenum and tungsten
GOST 18904.1−89
Group B59
STATE STANDARD OF THE USSR
TANTALUM AND ITS OXIDE
The photometric method for the determination of molybdenum and tungsten
Tantalum and its oxide. Photometrical method for determination
of molybdenum and tungsten
AXTU 1709
Valid from 01.01.90
to 01.01.95*
________________________________
* Expiration removed
Protocol N 4−93 inter-state Council
for standardization, Metrology and certification
(IUS N 4, 1994). — Note the manufacturer’s database.
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR
PERFORMERS
V. M. Vladimirov, N. Arakelian, B. M. Dobkin, R. F. Makarov, A. S. Terekhov
2. APPROVED AND put INTO EFFECT by Decision of the USSR State Committee for standards from
3. REPLACE GOST 18904.1−73, GOST 18904.2−73
4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
| The designation of the reference document referenced |
Section number, paragraph |
| GOST 3118−77 | 2 |
| GOST 3760−79 | 2 |
| GOST 3765−78 | 2 |
| GOST 4328−77 | 2 |
| GOST 10929−76 | 2 |
| GOST 17299−78 | 2 |
| GOST 18300−87 | 2 |
| GOST 18904.0−89 | 1.1 |
This standard sets the photometric method for determining the mass fraction of molybdenum and tungsten (from 0.004 inch to 0.04% of each), tantalum and its oxide.
The method is based on consecutive extraction amylacetate or chloroform colored complex compounds of molybdenum or tungsten with ditylum alikvotnih from different parts of the solution followed by measuring the optical density of the extracts.
1. GENERAL REQUIREMENTS
1.1. General requirements for method of analysis and security requirements — according to GOST 18904.0 with the addition of: analysis result should be the arithmetic mean of three parallel measurements, each of which perform a separate sample.
2. APPARATUS, REAGENTS AND SOLUTIONS
Photoelectrocolorimeter FEK-56 or similar.
Oven muffle.
Tile electric.
Nickel crucibles.
Separating funnel with a capacity of 50−75 cm.
Volumetric flasks with a capacity of 100 and 1000 cm.
Conical flasks with a capacity of 100 cm.
Pipettes with a capacity of 1.5 and 10 cm.
Microburette with a capacity of 5 cm.
Glasses chemical glass with a capacity of 50−100 cm.
Analytical scale.
Mortar and pestle porcelain.
Ammonia water according to GOST 3760.
Amylacetate.
Ammonium molybdate according to GOST 3765, H. h
Hydrogen peroxide according to GOST 10929, a solution with a mass concentration of 150 g/DM.
Tungsten metal.
Tungsten (VI) oxide.
Hydrochloric acid according to GOST 3118.
Molybdenum metal.
Sodium hydroxide according to GOST 4328 and a solution with a mass concentration of 100 g/DM.
Rectified ethyl alcohol according to GOST 18300 or technical ethyl alcohol (hydrolysis) according to GOST 17299, the highest purification.
The titanium metal.
Chloroform (trichlormethane).
Zinc-dithiol (3,4-dimercaptotoluene zinc salt).
Suspension zinc dithiol: a sample mass of 0.1 g zinc-dithiole moistened with alcohol, ground in porcelain mortar, add 25 cmof alcohol, before use, the suspension was shaken.
A solution of titanium chloride with a mass concentration of 150 g/DM: a sample weighing 0.5 g of titanium metal is placed in a beaker with a capacity of 25−50 cm
, add 10 cm
of hydrochloric acid, cover with watch glass, and dissolve by heating on the tile, adding hydrochloric acid to constant volume (10 cm
); the solution was stored in a dark bottle with a glass stopper not more than three days.
A standard solution of tungsten containing 0.1 mg of tungsten of 1 cmis prepared in one of two ways.
First method: a sample of tungsten with a mass of 0.1 g was placed in a beaker with a capacity of 200 cm, flow of 5−10 cm
of water, 20−25 cm
of hydrogen peroxide and heated to dissolve the sample, stirring occasionally. Then cautiously, drop by drop, add 2 cm
of ammonia and again heated to a decolorizing solution. After cooling, the solution was transferred to volumetric flask with a capacity of 1 DM
, adjusted to the mark with water and mix.
Second method: a sample of an oxide of tungsten with a mass of 0,1261 g, calcined to constant weight at 600−700 °C, were placed in a glass with a capacity of 100 cm, is dissolved in 20−25 cm
of sodium hydroxide solution, transferred to a volumetric flask with a capacity of 1 DM
, adjusted to the mark with water and mix.
A solution of a tungsten containing 0.01 mg of tungsten in 1 cm(working), prepared on the day of use by dilution of a standard solution with water in 10 times.
Standard molybdenum solution containing 0.1 mg of molybdenum of 1 cmis prepared in one of two ways.
First method: a sample of molybdenum with a mass of 0.1 g was placed in a beaker with a capacity of 100 cm, is dissolved in 5 cm
of hydrogen peroxide solution, add an excess of ammonia, the solution was heated to bleaching and removal of hydrogen peroxide. After cooling, the solution was transferred to volumetric flask with a capacity of 1 DM
, adjusted to the mark with water and mix.
The second method: ammonium molybdate hitch weight 1,840 g dissolved in water, transferred to a volumetric flask with a capacity of 1 DM, adjusted to the mark with water and mix.
Solution of molybdenum containing 0.01 mg of molybdenum in 1 cm(working), prepared on the day of use by dilution of a standard solution with water in 10 times.
3. ANALYSIS
3.1. A portion of the tantalum or its oxide with a mass of 0,3−0,5 g (with a mass fraction of molybdenum, up to 0.02% weighed 0.5 g) was placed in a Nickel crucible, which is pre-melted on the tile 1 g of sodium hydroxide, add 3 g of sodium hydroxide, put the crucible in a cold muffle furnace and bring the temperature to 800−850 °C and fused to a homogeneous melt. The crucible with the melt is cooled, the melt is treated with 60 cmof water when boiling.
After cooling the solution to precipitate transferred to a volumetric flask with a capacity of 100 cm, is diluted to the mark with water, mix thoroughly and leave to sludge precipitation. Two glasses with a capacity of 50−70 cm
is placed at 10−15 cm
clear solution, if necessary, add water up to 15 cm
, flow 15 cm
of hydrochloric acid and stirred.
3.1.1. For the determination of molybdenum in one of the glasses pour 2 cmof a suspension of zinc-dithiol and leave for 15 minutes, stirring occasionally. The solution was transferred to a separatory funnel with a capacity of 50 cm
, pour exactly 5 cm
of amylacetate or chloroform, shaken for 1 min; after the separation of the aqueous phase is discarded, the extract was transferred to a dry cuvette with a layer thickness of 3−10 mm (the cuvette with a layer thickness of 3−5 mm is used, if the mass of molybdenum over 14 µg), cover it with a lid and leave to stand until the disappearance of bubbles.
3.1.2. For the determination of tungsten in another glass add 10 drops of a solution of trichloride titanium (the appearance of a purple color). In the presence of molybdenum added 1.5 cmof freshly prepared titanium trichloride, leave for 10 minutes, stirring, and heated to boiling. The solution is cooled slightly, poured 1 cm
of a suspension of zinc-dithiol and transferred to a cylinder with a capacity of 50−70 cm
with glass stopper. The cylinder is placed in a glass of boiling water for 5−7 min. Then solution was cooled, transferred to a separatory funnel with a capacity of 50 cm
, flow from microburette or pipette with the piston 5 cm
of amylacetate or chloroform and shaken for 1 min. After separation the aqueous phase is discarded, the extract was transferred to a dry cuvette with a layer thickness of 5−10 mm (cuvette with a layer thickness of 5 cm is used, if the mass of tungsten over 24 mcg), cover and leave to stand until the disappearance of bubbles (about 1 minute).
3.1.3. The optical density of the extracts is measured on photoelectrocolorimeter at a wavelength of 630 nm. A solution of comparison used water. At the same time through the analysis of spend control experience. Optical density of the solution in the reference experiment must not exceed the value of 0.01. A lot of molybdenum and tungsten find for the calibration graphs.
3.2. Construction of calibration graphs
3.2.1. Preparation of solutions for determination of molybdenum
In glasses with a capacity of 50 cmimpose 0,3; 0,5; 0,7; 0,9; 1,0; 1,5; 2,0; 2,5; 3,0 cm
working solution of molybdenum, poured water up to 15 cm
, 15 cm
of hydrochloric acid and stirred. Further, determination is carried out according to PP.3.1.1,
3.2.2. Preparation of solutions for determination of tungsten
In glasses with a capacity of 50 cmimpose 0,3; 0,5; 0,7; 1,0; 1,5; 2,0; 3,0; 4,0; 5,0 cm
working solution of tungsten, poured water up to 15 cm
, 15 cm
of hydrochloric acid. After adding each reagent every solution is thoroughly mixed. Further, determination is carried out according to PP.3.1.2 and
3.2.3. On the measured values of the optical density of each of the solutions of comparison and corresponding values of the mass of molybdenum or tungsten build the calibration graphs along with the analysis of a series of samples.
4. PROCESSING OF THE RESULTS
4.1. Mass fraction of molybdenum or tungsten in percent () is calculated by the formula
where is the mass of molybdenum (tungsten), was found in the calibration graphics mg;
— volume of the volumetric flask, cm
;
— the weight of the portion of the sample, mg;
— volume aliquote part of the solution, cm
.
4.2. The absolute value of the difference between the largest and smallest results of parallel measurements, and the absolute value of the difference of two analysis results with a probability of 0.95 does not exceed the permissible differences given in table.
| Mass fraction of molybdenum (tungsten), % |
Allowable difference, % |
| 0,004 |
0,001 |
| 0,01 |
0,002 |
| 0,02 |
0,003 |
| 0,04 |
0,005 |
4.3. Allowed the use of other techniques of analysis on metrological characteristics are not inferior to mentioned in the standard.
4.4. If there is disagreement in the determination of molybdenum and tungsten used photometric method of analysis.
