GOST 9816.1-84

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  ГОСТ 9816.1-84

GOST 9816.1−84 Tellurium technical. Method for the determination of tellurium (with Amendments No. 1, 2)

GOST 9816.1−84

Group B59

STATE STANDARD OF THE USSR

TELLURIUM TECHNICAL

Method for the determination of tellurium

Technical tellurium. Method for determination of tellurium

AXTU 1709

Valid from 01.07.85
before 01.07.90

The decision of the State Committee USSR on standards on June 27, 1984 N 2149 validity period is set with 01.07.85 before 01.07.90*
________________
* Expiration removed by Protocol No. 4−93 of the Interstate Council for standardization, Metrology and certification (I & C N 4, 1994). — Note the manufacturer’s database.


REPLACE GOST 9816.1−74


MADE: the Change in N 1, approved and put into effect by the Decree of Gosstandart of the USSR from 20.12.1989 N c 3908 01.07.1990; Modification No. 2, approved and promulgated by the Order of Rosstandart from 26.11.2014 No. 1770-St c 01.09.2015

Change N 1, 2 made by the manufacturer of the database in the text IUS N 3, 1990, IUS N 3, 2015

This standard specifies the titrimetric method for the determination of tellurium at its mass fraction from 96,0% and above in technical tellurium.

The method is based on the oxidation of tetravalent tellurium to the hexavalent solution of potassium dichromate.

(Changed edition, Rev. N 2).

1. GENERAL REQUIREMENTS

1.1. General requirements for method of analysis according to GOST 9816.0−84.

1A. NORMATIVE REFERENCES

This standard uses the regulatory references to the following international standards:

GOST 1770−74 laboratory Glassware measuring glass. Cylinders, beakers, flasks, test tubes. General specifications

GOST 3118−77 Reagents. Hydrochloric acid. Specifications

GOST 4204−77 Reagents. Sulphuric acid. Specifications

GOST 4208−72 Reagents. Salt of protoxide of iron and ammonium double sulfate (salt Mora). Specifications

GOST 4220−75 Reagents. Potassium dichromate. Specifications

GOST 4461−77 Reagents. Nitric acid. Specifications

GOST 6552−80 Reagents. Orthophosphoric acid. Specifications

GOST 6709−72 distilled Water. Specifications

GOST 9816.0−84 Tellurium technical. General requirements for methods of analysis

GOST 24104−2001* laboratory Scales. General technical requirements
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* On the territory of the Russian Federation GOST R 53228−2008 «Scales non-automatic actions. Part 1. Metrological and technical requirements. Test».


GOST 25336−82 Glassware and equipment laboratory glass. The types, basic parameters and dimensions

GOST 29251−91 (ISO 385−1-84) oils. Burette. Part 1. General requirements

GOST ISO 5725−6-2002** Accuracy (trueness and precision) of methods and measurement results. Part 6. The use of precision values in practice
_______________
** On the territory of the Russian Federation GOST R ISO 5725−6-2002 «Accuracy (trueness and precision) of methods and measurement results. Part 6. The use of precision values in practice».


Note — When using this standard appropriate to test the effect of reference standards in the information system of General use — on the official website of the Federal Agency for technical regulation and Metrology on the Internet or published annually by the information sign «National standards» published as on January 1 of the current year and related information published monthly indexes published in the current year. If the reference standard is replaced (changed), when using this standard should be guided by replacing (amended) standard. If the reference standard is cancelled without replacement, then the situation in which the given link applies to the extent that does not affect this link.

1A (optionally Entered, Rev. N 2).

1B. CHARACTERISTICS OF INDICATORS OF MEASUREMENT ACCURACY

A measure of the accuracy of measuring the mass fraction of tellurium corresponds to the characteristics given in table 1 (if of 0.95).

Limit values of repeatability and reproducibility of measurements for a confidence probability of 0.95 is given in table 1.


Table 1

Percentage

1B (Introduced later, Rev. N 2).

2. MEASUREMENT MEANS, AUXILIARY DEVICES, MATERIALS, SOLUTIONS

When performing measurements using the following measuring instruments and auxiliary devices:

— the stove is electric with a closed heating element for temperature up to 400 °C;

— special laboratory scales of accuracy class according to GOST 24104;

— drying Cabinet, providing a heating temperature of from 100 °C to 105 °C;

— volumetric flasks 2−1000−2 according GOST 1770;

— flasks KN-2−500−29/32 according to GOST 25336;

— glasses-1−400 TCS In-1−600 TCS according to GOST 25336;

— burette I-2−25−0,1; I-2−50−0,1 according to GOST 29251;

— hour glass.

When performing measurements, use the following materials, solutions:

— distilled water according to GOST 6709;

— nitric acid according to GOST 4461;

— sulfuric acid according to GOST 4204, diluted 1:1 and a solution of 0.5 mol/DM;

— hydrochloric acid according to GOST 3118;

— phosphoric acid according to GOST 6552;

Sol of oxide of iron and ammonium double sulfate (salt Mora) according to GOST 4208, solution of molar concentration 0.1 mol/DM;

— potassium dichromate according to GOST 4220, solution of molar concentration 0.1 mol/DM;

— diphenylamine-4-sulfonic acid sodium salt (two sodium sulfonate), the indicator according to [1], a solution of 2 g/DM.

(Changed edition, Rev. N 1, 2).

2A. PREPARATIONS FOR THE MEASUREMENTS

2A.1. In the preparation of the salt solution Mora molar concentration of 0.1 mol/DM: fixanal salt or Mora of 39.2 g of salt is dissolved in 200 cmof sulfuric acid solution of molar concentration 0.5 mol/DM, the resulting solution is placed in a measuring flask with volume capacity of 1000 cm, adjusted to the mark with water and mix.

The solution is stable for three months.

2A.2. In the preparation of a solution of potassium dichromate molar concentration of 0.1 mol/DMfixanal of potassium dichromate or 4,9032 g of salt (previously recrystallized and dried at a temperature of from 150 °C to 160°C) dissolved in a volume of 200 to 300 cmof water, put the solution into a measuring flask with volume capacity of 1000 cm, adjusted to the mark with water and mix.

The solution is steady throughout the year.

1 cmof the mortar is 0,006380 g of tellurium.

2A.3. In preparing the solution difenilgidantoina sodium with a mass concentration of 2 g/DM2 g difenilgidantoina sodium is dissolved in 1000 cmof water. The solution should be stored in a flask made of dark glass.

2A.4. Setting the ratio of the concentrations of solutions of potassium dichromate and salt Mora

In a conical flask with a capacity of 500 cmis placed 20 to 25 cm(from burette) solution of potassium dichromate, is added 180 to 200 cmwater, 10 cmof hydrochloric acid, 20 cmof sulfuric acid solution, diluted 1:1, 5 cmof phosphoric acid and titrated with a solution of salt Mora in the presence of 1−2 cmof solution difenilgidantoina sodium until the solution colour from purple to green.

2A (Introduced later, Rev. N 2).

3. ANALYSIS

3.1. A portion of the tellurium mass of 0.25 g is placed in a beaker with a capacity of 300−400 cm, moistened with 3−5 drops of water, add 6 cmof hydrochloric acid and 2 cmof nitric acid, cover with a glass lid and maintained at a temperature of (20±5)°C until complete dissolution of the sample, then add 10 cmof hydrochloric acid and heat the solution for 30−40 min to remove the oxides of nitrogen.

After heating the lid and the side of the Cup is washed with 10−20 cmof water and the solution was heated 15 min. a glass with a solution, cooled to a temperature of (20±5)°C and transfer the contents into a glass with a capacity of 600 cmcontaining 50 cmof a solution of potassium dichromate and 20−30 cmof water. The volume of solution is 200 to 250 cm. The solution is kept at a temperature of (20±5)°C for 30−40 min. Poured 20 cmof sulphuric acid (1:1), 5 cmof phosphoric acid, stirred and titrated with a solution of salt Mora until the solution colour to yellow-green.

Add 1−2 cmof the indicator solution and continue the titration with Mohr salt solution until the color of the solution from purple to green.

(Changed edition, Rev. N 1, 2).

3.2. (Deleted, Rev. N 2).

4. PROCESSING OF THE RESULTS

4.1. Mass fraction of tellurium (X) in percent is calculated by the formula

,

where T is the mass concentration of a solution of potassium dichromate, g/cmof tellurium;

K — the ratio of the concentrations of solutions of potassium dichromate and Mohr salts ;

 — the volume of salt solution Mora, cm;

 — the volume of solution of potassium dichromate, cm;

m — weight of tellurium,

(Changed edition, Rev. N 1).

4.2. The measurement results take the arithmetic mean value of three parallel measurements, provided that the difference between the highest and the lowest results in terms of repeatability with a confidence level of 0.95 does not exceed the limit values of the frequency of occurrence , are given in table 1.

If the difference between the highest and lowest results of parallel measurements exceeds the limit value of the frequency of occurrence, perform the procedure described in GOST ISO 5725−6 (paragraph 5.2.2.1).

(Changed edition, Rev. N 1, 2).

4.3. The absolute value allowable discrepancies between the two measurement results obtained in different laboratories, should not exceed the values of the limit of reproducibility given in table 1 at a confidence level of 0.95. At default of this condition can be used the procedure set out in GOST ISO 5725−6.

(Added, Rev. N 2).

Bibliography

Bibliography (added, Rev. N 2).