GOST 22974.3-96

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  ГОСТ 22974.3-96

GOST 22974.3−96 fused welding Fluxes. Methods for determining manganese oxide (II)

GOST 22974.3−96

Group B09

INTERSTATE STANDARD

FUSED WELDING FLUXES

Methods for determining manganese oxide (II)

Melted welding fluxes.
Methods of manganous oxide (II) determination

ISS 77.040
AXTU 0809

Date of implementation 2000−01−01

Preface

1 DEVELOPED by the Interstate technical Committee for standardization MTK 72; the Institute of electric them. E. O. Paton of NAS of Ukraine

SUBMITTED to the State Committee of Ukraine for standardization, Metrology and certification

2 ADOPTED by the Interstate Council for standardization, Metrology and certification (Protocol No. 9 dated April 12, 1996)

The adoption voted:

3 Resolution of the State Committee of the Russian Federation for standardization and Metrology, dated April 21, 1999 N 134 inter-state standard GOST 22974.3−96 introduced directly as state standard of the Russian Federation from January 1, 2000

4 REPLACE GOST 22974.3−85

1 Scope

This standard sets the potentiometric method for determining manganese oxide (II) (if the mass fraction of manganese oxide (II) from 2 to 50%), photometric method for determining manganese oxide (II) (if the mass fraction of manganese oxide (II) from 0.1 to 10%) and atomic absorption method for the determination of manganese oxide (II) (if the mass fraction of manganese oxide (II) from 0.1 to 50%).

2 Normative references

The present standard features references to the following standards:

GOST 342−77 Sodium phosphate Piro. Specifications

GOST 1277−75 Silver nitrate. Specifications

GOST 3118−77 hydrochloric Acid. Specifications

GOST 3760−79 Ammonia water. Specifications

GOST 4204−77 sulfuric Acid. Specifications

GOST 4461−77 nitric Acid. Specifications

GOST 5457−75 Acetylene, dissolved and gaseous. Specifications

GOST 6008−90 metallic Manganese and nitrated manganese. Specifications

GOST 6552−80 orthophosphoric Acid. Specifications

GOST 18300−87 ethyl rectified technical. Specifications

GOST 20478−75 Ammonium neccersarily. Specifications

GOST 20490−75 Potassium permanganate. Specifications

GOST 22974.0−96 fused welding Fluxes. General requirements for methods of analysis

GOST 22974.1−96 fused welding Fluxes. Methods of flux decomposition

3 General requirements

General requirements for methods of analysis GOST 22974.0.

4 Potentiometric method for determining manganese oxide (II)

4.1 the essence of the method

The method is based on the oxidation of ions of bivalent manganese with potassium permanganate to trivalent in a neutral environment in the presence of pyrophosphate of sodium. In the equivalent point there is a jump of potential indicates the end of the reaction.

4.2 Equipment, reagents and solutions

The setup for potentiometric titration.

Millivoltmeter by 17−20 mV internal resistance 700 Ohms.

Mixers with a speed of 8.3 and 10.0 with(500−600 rpm) or magnetic stirrer.

Electrodes: as cathode, a platinum electrode used as the anode — tungsten electrode, diameter of the electrodes of 0.8−1.0 mm, length 100−120 mm. Before titration, the electrode is cleaned with fine emery paper.

Nitric acid according to GOST 4461.

Hydrochloric acid according to GOST 3118, diluted 1:1.

Ammonia water according to GOST 3760, diluted 1:1.

Sodium pyrophosphate according to GOST 342, solution mass concentration of 0.07 g/cm.

The technical rectified ethyl alcohol according to GOST 18300.

Neutral red, indicator: 0.1 g of the indicator is dissolved in 60 cmof ethyl alcohol and diluted to 100 cmwith water.

Manganese metal according to GOST 6008, the degree of purity of at least 99.95%: 10 g of manganese placed in a beaker with a capacity of 400 cm, was treated within a few minutes the surface layer of a mixture of 50 cmwater and 5 cmof nitric acid to obtain a shiny surface. Manganese is washed six times with water, then with acetone and dried at 100 °C for 10 min.

Standard solutions of manganese oxide (II).

Solution a: 0,7744 g of metallic manganese, purified from the oxide film is dissolved by heating in 20 cmof hydrochloric acid carefully drop by drop pour 1−2 cmof nitric acid and boil to remove oxides of nitrogen. The solution was cooled, transferred to a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix. Solution a has a mass concentration of oxide manganese (II) 0,001 g/cm.

Solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. Solution B has a mass concentration of oxide manganese (II) 0.0001 g/cm.

Potassium permanganate according to GOST 20490 with molar concentration of equivalent of 0.05 mol/DM: 1.6 g of potassium permanganate dissolved in 1 DMof water. The solution is poured into a bottle made of dark glass and leave it for 8−10 days, then decanted or filtered through an asbestos filter in a bottle of dark glass. The mass concentration is set no earlier than the following day.

Standard solution of manganese oxide (II) can be prepared from potassium permanganate.

Solution a: 2,2279 g of potassium permanganate, precrystallisation and air-dried, placed in a beaker with a capacity of 300−400 cm, 100 cm pouredwater, heated until complete dissolution. Then pour the hydrochloric acid until complete discoloration of the solution. The solution was evaporated to dryness. The dry residue is dissolved in 40 cmof hydrochloric acid (1:1), transferred to a measuring flask with volume capacity of 1000 cm, made up to the mark with water and mix. Solution a has a mass concentration of oxide manganese (II) 0,001 g/cm.

Solution B: 10 cmsolution And placed in a volumetric flask with a capacity of 100 cm, made up to the mark with water and mix. The solution has a mass concentration of oxide manganese (II) 0.0001 g/cm.

Set the mass concentration of potassium permanganate solution: select 20 cmof the standard solution And in a glass with a capacity of 400−500 cmcontaining 150 cmof sodium pyrophosphate solution, add three drops of neutral red indicator and neutralize with ammonia (1:1) until the reddish-brown color. The solution volume was adjusted with water to 250 cm, lower electrodes, include the stirrer and titrate with 0.05 mol/DMsolution of potassium permanganate until a sharp jump of potential.

Upon completion of the work leave the electrodes immersed in the glass of water.

The mass concentration of a solution of potassium permanganate , g/cmmanganese oxide (II), calculated by the formula

, (1)

where  — the weight of the portion of oxide manganese (II), corresponding to aliquote part of the solution, g;

 — the volume of 0.05 mol/DMof potassium permanganate solution consumed for titration, sm.

4.3 analysis

After the decomposition flux according to GOST 22974.1 25 cmof the solution was placed in a beaker with a capacity of 400−500 cmcontaining 150 cmof sodium pyrophosphate solution, add three drops of neutral red indicator and neutralize with ammonia (1:1) until the reddish-brown color. The solution volume was adjusted with water to 250 cm, lower electrodes, include the stirrer and titrate with 0.05 mol/DMsolution of potassium permanganate until the sharp jump of potential.

4.4 Processing of results

Mass fraction of manganese oxide (II) , %, is calculated by the formula

, (2)

where is the volume of potassium permanganate solution consumed for titration of sample, cm;

 — the volume of potassium permanganate solution consumed for titration of the control experience, cm;

 — mass concentration of the potassium permanganate solution, in g/cmmanganese oxide (II);

 — the weight of the portion of the flux corresponding to aliquote part of the solution, g

.

4.5 Norms of accuracy and norms control the accuracy of determining manganese oxide (II) are given in table 1.


Table 1

Percentage

5 Photometric method for determining manganese oxide (II)

5.1 the essence of the method

The method is based on the oxidation of divalent manganese in an acidic medium to pneumococcal neccersarily ammonium in the presence of silver nitrate or potassium ignobilis in the presence of phosphoric acid. The optical density of colored solution is measured at a wavelength of 545 nm (green filter).

5.2 Equipment, reagents and solutions

Spectrophotometer or photoelectrocolorimeter.

Nitric acid according to GOST 4461.

Orthophosphoric acid according to GOST 6552.

Sulfuric acid according to GOST 4204, diluted 1:1.

Ammonium neccersarily according to GOST 20478, solution mass concentration of 0.15 g/cm.

Cognately potassium or sodium cognately.

Silver nitrate according to GOST 1277, solution mass concentration of 0.01 g/cm.

Water, not containing reducing agents: to 1000 cmof water are added 5 cm.of sulfuric acid diluted 1:1, heated to boiling, add a few crystals of potassium jednolitego and boiled for 10 min.

Standard solution of manganese oxide (II).

Solution: 10 cmof solution A, prepared according to 4.2, transferred to a beaker with a capacity of 300−400 cm, flow 10 cmof sulphuric acid and evaporate to dense fumes of sulfuric acid. The glass is cooled, washed wall with water and the evaporation repeated. After cooling, the solution is transferred to a volumetric flask with a capacity of 500 cmand was adjusted to the mark with water. The solution has a mass concentration of oxide manganese (II) 0,00002 g/s

m.

5.3 analysis

5.3.1 After the decomposition flux according to GOST 22974.1 50 cmsolution (100 cmfor the mass concentration of manganese oxide (II) less than 0.5%) were placed in a glass with a capacity of 300−400 cm, add 5 cmof nitric acid, 10 cmof sulphuric acid and evaporate to dense fumes of sulfuric acid. The glass is cooled, washed wall with water and the evaporation repeated. The solution was cooled, transferred to a volumetric flask with a capacity of 250 cm, was adjusted to the mark with water and mix.

5.3.2 Oxidation of manganese neccersarily ammonium

Select the 10 cmmortar (20 cmwhen the mass fraction of manganese oxide (II) less than 0.5%) in a volumetric flask with a capacity of 100 cm, flow 10 cmwater, 10 cmof silver nitrate and 20 cmnaternicola ammonium. The solution is heated to boiling, cooled, adjusted to the mark with water, mixed and kept for 20 min to complete development of color.

Optical density of the solution measured on a spectrophotometer at a wavelength of 545 nm or photoelectrocolorimeter with a green optical filter in a ditch with thickness of the absorbing layer 30 mm.

As a solution the comparison serves as a test sample drawn through the entire course of the analysis.

Weight of manganese oxide (II) find the calibration schedule.

5.3.3 Construction of calibration curve

In ten volumetric flasks with a capacity of 100 cmconsistently make 1; 2; 4; 6; 8; 10; 12; 14; 16 and 20 cmstandard solution, which corresponds to 0,00002; 0,00004; 0,00008; 0,00012; 0,00016; 0,00020; 0,00024; 0,00028; 0,00032; 0,00040 g of manganese oxide (II).

In the eleventh flask make a 3−5 cmof sulphuric acid (1:1), add 10 cmof water and lead further analysis, as specified in 5.3.2. Solution comparison is the solution, in which there is no standard solution manganese oxide.

5.3.4 Oxidation of manganese hodnoceni potassium (sodium)

Select the 10 cmmortar (20 cmwhen the mass fraction of manganese oxide (II) less than 0.5%), transferred to a conical flask with a capacity of 150 cm(if taken aliquota part 10 cm, then add 10 cmof water), poured 3 cmof phosphoric acid, add 0.25 g jednolitego potassium or sodium. The contents of the flask heated to boiling, boil for 3−5 min and left in a water bath at a temperature of approximately 90 °C for 40−50 min. Then solution was cooled, transferred to a volumetric flask with a capacity of 100 cm, top up with water containing no reducing agents to the mark and mix.

Optical density of the solution measured on a spectrophotometer at a wavelength of 545 nm or photoelectrocolorimeter with a green optical filter in a ditch with thickness of the absorbing layer 30 mm.

As a solution the comparison serves as a test sample drawn through the entire course of the analysis.

Weight of manganese oxide (II) find the calibration schedule

.

5.3.5 Construction of calibration curve

In ten volumetric flasks with a capacity of 100 cmconsistently make 1; 2; 4; 6; 8; 10; 12; 14; 16 and 20 cmstandard solution, which corresponds to 0,00002; 0,00004; 0,00008; 0,00012; 0,00016; 0,00020; 0,00024; 0,00028; 0,00032 and 0,00040 g of manganese oxide (II), in the eleventh flask make a 3−4 cmof sulphuric acid (1:1), add 10 cmof water and lead further analysis, as specified in 5.3.4. Solution comparison is the solution, in which there is no standard solution manganese oxide (II).

5.4 processing of the results

Mass fraction of manganese oxide (II) , %, is calculated by the formula

, (3)

where is the mass of manganese oxide (II) found by calibration schedule g;

 — the weight of the portion of the flux corresponding to aliquote part of the solution,

5.5 the Norms of accuracy and norms control the accuracy of determining the mass fraction of manganese oxide (II) are given in table 1.

6 Atomic absorption method of determining manganese oxide (II)

6.1 the essence of the method

The method is based on measuring the degree of absorption of resonance radiation by free atoms of manganese, resulting from the spraying of the solution into the flame air-acetylene. To determine the mass fraction of manganese oxide (II) up to 5% is used the resonance line of 279.5 nm. To determine the mass fraction of manganese oxide (II) more than 5% is less sensitive line 403,0 nm.

6.2 Apparatus, reagents and solutions

Atomic absorption spectrophotometer with flame atomizer.

Lamp with hollow cathode for determining manganese oxide (II).

Acetylene, dissolved and gaseous technical GOST 5457.

Hydrochloric acid according to GOST 3118, diluted 1:1.

Potassium permanganate according to GOST 20490.

Manganese metal according to GOST 6008.

Standard solutions of manganese oxide (II) are prepared according to 4.2.

6.3 Preparation for analysis

Prepare the instrument: set the spectrophotometer at a resonance line of 279.5 nm or 403,0 depending on the content of manganese oxide (II) in the flux (table 2).

6.4 analysis

After the decomposition flux according to GOST 22974.1 5−20 cmof solution (depending on the mass fraction of manganese oxide (II), table 2) is transferred to a volumetric flask with a capacity of 100 cm, pour 5 cmof hydrochloric acid (1:1), made up to the mark with water and mix.


Table 2

Is sprayed into the flame of the solution in the reference experiment, and then analyze the solution.

Prior to introduction into the flame of each solution is sprayed water to wash the system and check the zero point.

Since the range in the range of the calibration graphs depends on the sensitivity of the employed equipment, we offer masses of elements to determine in the samples for constructing the calibration graphs should be considered recommended.

6.5 Construction of calibration curve

6.5.1 Construction of calibration curve for the mass fraction of manganese oxide (II) from 0.1 to 5.0%

In a volumetric flask with a capacity of 100 cmplaced 1; 2; 4; 6; 8 and 10 cmof a standard solution of manganese oxide (II) B prepared according to 4.2, which corresponds to 0,0001; 0,0002; 0,0004; 0,0006; 0,0008; 0,0010 g of manganese oxide (II), pour 5 cmof hydrochloric acid (1:1), made up to the mark with water and mix.

Set up the device on resonance line of 279.5 nm.

The solutions were sprayed in order of increasing removals. Before spraying each solution is sprayed water.

6.5.2 Construction of calibration curve for the mass fraction of manganese oxide (II) from 5 to 50%

In a volumetric flask with a capacity of 100 cmplaced 1; 2; 4; 6; 8 and 10 cmof a standard solution of manganese oxide (II) And prepared according to 4.2, which corresponds to 0,001; 0,002; 0,004; 0,006; 0,008 and 0,010 g of manganese oxide (II), pour 5 cmof hydrochloric acid (1:1), made up to the mark with water and mix.

Set up the device on resonance line 403,0 nm.

The solutions were sprayed in order of increasing removals.

Before spraying each solution is sprayed water.

6.6 processing of the results

6.6.1 From the average value of absorbance of each of the analyzed solutions, the average value is subtracted absorption in the reference experiment.

According to the calibration schedule find the mass percent of manganese oxide (II) in grams.

6.6.2 Mass fraction of oxide of manganese , %, is calculated by the formula

, (4)

where is the mass of manganese oxide (II) found by calibration schedule g;

 — the weight of the portion of the flux corresponding to aliquote part of the solution,

6.7 Standards of accuracy and standards for monitoring the accuracy of determining the mass fraction of manganese oxide (II) are given in table 1.