GOST 16274.7-77

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  ГОСТ 16274.7-77

GOST 16274.7−77 Bismuth. Method for the determination of zinc content (with Amendments No. 1, 2, 3)

GOST 16274.7−77

Group B59

STATE STANDARD OF THE USSR

BISMUTH

Method for the determination of zinc content

Bismuth.
Method for determination of zinc 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 16274.7−70

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 polarographic method for the determination of zinc content (with zinc content of 0.001 to 0.02%).

The method is based on polarography zinc chloride-ammonia background in the range of potentials from minus 1.3 to minus 1.6 V relative to the bottom of mercury or a saturated calomel electrode. Bismuth is separated from the zinc by dissolving it in mercury; the zinc and other impurities remain in solution.

(Changed edition, Rev. N 3).

1. GENERAL REQUIREMENTS

General requirements for method of analysis according to GOST 16274.0

2. APPARATUS, REAGENTS AND SOLUTIONS

Volumetric flasks with a capacity of 1,000, 50 cmaccording to GOST 1770.

Polarograph polarograph oscilloscope or AC of any type.

Mercury brand RO according to GOST 4658.

Bismuth brand or Ви0000 Ви000 according to GOST 10928.

Zinc metal granulated.

Ammonium chloride according to GOST 3773.

Ammonia water according to GOST 3760.

Nitric acid according to GOST 4461.

Hydrochloric acid according to GOST 3118 and the solution with molar concentration of 2 mol/DM.

Gelatin food according to GOST 11293, 1% solution.

Sanitarily sodium (sodium sulfite) crystal on the other 6−09−5313, saturated solution.

A solution of chloride of bismuth in hydrochloric acid solution with molar concentration of 2 mol/DMis prepared as follows: 1 g of bismuth brand or Ви0000 Ви000 dissolved in 10 cmof concentrated nitric acid and evaporate to dryness, add 5 cmof hydrochloric acid and evaporated to moist salts. Then salt is dissolved in a hydrochloric acid solution with molar concentration of 2 mol/DM, the solution is transferred into a measuring flask with volume capacity of 1000 cmand pour the hydrochloric acid solution with molar concentration of 2 mol/DMup to the mark.

1 cmof the solution contains 1 mg of bismuth.

Hloridnaja background; prepared as follows: 100 mg of ammonium chloride, 100 CCof ammonia and 100 cmof a saturated solution of sodium sulfite is diluted with water to 1000 cm. Before polarographically add three drops of 1% gelatin solution.

Standard solution of zinc; prepared as follows: 0.1 g of zinc is dissolved in a volumetric flask with a capacity of 1000 cm40 cmof concentrated hydrochloric acid. The solution was topped to the mark with water and mix.

1 cmof the solution contains 0.1 mg of zinc.

Calibration solutions of zinc in four volumetric flasks with a capacity of 50 cmis placed 0,5; 1,5; 5,0 and 10,0 cmstandard solution of zinc, pour 10 cmof a solution of bismuth chloride and made up to label a chloride-ammonia background.

The calibration solutions contain 1,0; 3,0; 10,0 and 20,0 mg of zinc in 1 cm.

Indicator paper «Congo».

(Changed edition, Rev. N 2, 3).

3. ANALYSIS

A sample of bismuth with a mass of 5 g is placed in a conical flask and dissolved in 4 cmof mercury, at the same time priliva 10 cmof bismuth chloride, then heat the solution in a fume hood for work with mercury to low simmer and stirred 10−15 min.

The solution was filtered through an ordinary filter and washed 2−3 times with water, the filtrate neutralized by the indicator paper «Congo» ammonia, poured into a volumetric flask with a capacity of 50 cm, made up to the mark chloride-ammonia background and polarographic zinc when applying to the electrodes a voltage in the range from minus 1.3 to minus 1.6 In (relative to the bottom of mercury or saturated calomel electrode).

(Changed edition, Rev. N 3).

4. PROCESSING OF THE RESULTS

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

,

where is the mass concentration of zinc in the calibration solution micrograms/cm;

 — height of the test solution, mm;

 — the total volume of the analyzed solution, cm;

 — hitch, g;

 — wave height of the calibration solution;

1000000 — conversion factor from grams to micrograms.

(Changed edition, Rev. N 2, 3)

.

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:

for the range of mass fraction from 0.001 to 0.003%;

for the interval mass fraction of more than 0,003%,

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).