GOST 16274.6-77

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  ГОСТ 16274.6-77

GOST 16274.6−77 Bismuth. Method for determination of iron content (with Amendments No. 1, 2, 3)

GOST 16274.6−77

Group B59

STATE STANDARD OF THE USSR

BISMUTH

Method for determination of iron content

Bismuth.
Method for determination of iron content

AXTU 1709

Date of introduction 1978−01−01

INFORMATION DATA

1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR

DEVELOPERS

PS Poklonsky, F. M. Manji, G. V. Khabarova

2. APPROVED AND promulgated by the DECREE of the State Committee of standards of Ministerial Council of the USSR from 25.01.77 N 172

3. The frequency of inspection 5 years

4. REPLACE GOST 16274.6−70

5. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS

6. Resolution of the state standard from 30.07.92 N 836 removed the limitation of the validity period

7. Reprint (July 1997) with Amendments No. 1, 2, 3, approved in January 1983, June 1987, July 1992 (IUS 5−83, 11−87, 10−92)


This standard applies to metallic bismuth brands Vi1 and Vi2 and sets the colorimetric method for the determination of iron content (with Fe content of from 0.001 to 0.01%).

The method is based on colorimetric determination of iron by the red color of iron thiocyanate extracted in the organic layer. Bismuth is not separated, the determination of iron produced in the hydrochloric acid environment.

(Changed edition, Rev. N 3).

1. GENERAL REQUIREMENTS

1.1. General requirements for method of analysis according to GOST 16274.0.

2. GLASSWARE, REAGENTS AND SOLUTIONS

Volumetric flasks with a capacity of 1,000, 250, 100 cmaccording to GOST 1770.

Microburette with a capacity of 5 cmin the NTD.

The colorimetric cylinders.

Separating funnel with a capacity of 100 cm.

The beakers, Pyrex, with capacity of 100 cmaccording to GOST 7851.

Pipettes with a capacity of 10 cmfor NTD.

Nitric acid according to GOST 4461, H. h., diluted 1:1.

Hydrochloric acid according to GOST 3118, H. C., and diluted 1:9.

Ammonium radamisty according to GOST 27067, 30% solution.

A solution of ammonium thiocyanate, purified from iron by extraction with a mixture of diethyl ether and isoamyl alcohol in the ratio 1:1.

Bismuth metal brand Ви0000 or Ви000 according to GOST 10928.

Diethyl ether (medical).

Isoamyl alcohol according to GOST 5830.

Iron oxide on the other 6−09−5331.

Standard iron solution

Solution 1; prepared as follows: 0,3574 g of iron oxide was dissolved with heating in 50 cmof hydrochloric acid. The solution was cooled, poured into a volumetric flask with a capacity of 250 cm, made up to the mark with water and mix.

1 cmof the solution contains 1 mg of iron.

Solution 2; prepared as follows: 10 cmof solution 1 is placed in a volumetric flask with a capacity of 100 cm, made up to the mark with hydrochloric acid diluted 1:9, and stirred.

1 cm2 of solution contains 0.1 mg of iron.

Solution 3; prepared as follows: 10 cmsolution of 2 placed in a volumetric flask with a capacity of 100 cm, made up to the mark with hydrochloric acid diluted 1:9, and stirred.

1 cm3 of the solution contains 0.01 mg of iron.

Reference solution prepared as follows: 1 g of bismuth brand or Ви0000 Ви000 placed in a beaker with a capacity of 100 cm, is dissolved in 5 cmof nitric acid, diluted 1:1, and evaporated to dryness. Pour 40−50 cmof hydrochloric acid, diluted 1:9, after the solids are dissolved, the solution transferred to a volumetric flask with a capacity of 100 cm, made up to the mark with hydrochloric acid diluted 1:9, and stirred.

(Changed edition, Rev. N 2, 3).

3. ANALYSIS

A portion of the bismuth of 1 g was placed in a beaker with a capacity of 100 cm, add 5 cmof nitric acid, diluted 1:1, and dissolved, after which the solution was evaporated to dryness. Then add 40−50 cmof hydrochloric acid, diluted 1:9 and after dissolution of the precipitate the solution was transferred to a volumetric flask with a capacity of 100 cm.

The solution in the flask topped up to the mark with hydrochloric acid diluted 1:9, and stirred.

One cylinder for colorimetrically select 20 cmof the analyzed solution and the other with a cylinder of 20 cmof solution comparison.

In both cylinders simultaneously measured with a pipette of 1 cm30% solution of ammonium thiocyanate, 5 cmof a mixture of ether and alcohol and mix the solutions. Into the cylinder with a solution comparison refills from microburette standard solution 3 to align the colors spincoating layers in both cylinders.

(Changed edition, Rev. N 3).

4. PROCESSING OF THE RESULTS

4.1. The iron content in the bismuth () in percent is calculated by the formula

,

where  — the amount of iron in the standard solution 3, used for titration, mg;

 — the total volume of solution, cm;

 — hitch, g;

1000 — conversion factor for grams to milligrams;

 — aliquota part of the solution, taken for colorimetrically, cm.

4.2. The maximum discrepancy between the results of three parallel measurements () and the results of two tests () at a confidence probability of 0.95, should not exceed the values given in the table.

Permitted discrepancies for the intermediate mass fraction calculated using linear interpolation or according to the formulas:



,

where is the arithmetic mean of results of three parallel measurements;

 — the arithmetic mean of the results of the two tests.

(Changed edition, Rev. N 3).