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GB 10735-2008Primary chemical - Sodium carbonate anhydrous (English PDF)

第一基准试剂无水碳酸钠

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Issued by

General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China; Standardization Administration of China

Level / Type

National · Mandatory

Issue date

June 18, 2008

Implementation date

June 1, 2009

Scope

GB 10735-2008 is the English-translated version of 第一基准试剂无水碳酸钠.

China's mandatory national standard for anhydrous sodium carbonate as a primary chemical. Anhydrous sodium carbonate is the primary standard for acid, the counterpart of potassium hydrogen phthalate on the other side of the neutralisation: it is what standardises the hydrochloric and sulfuric acid solutions used in every titration laboratory. Its qualification as a primary standard depends entirely on one thing that has to be done right, and the standard says so - it must be dried to constant weight at around 270 to 300 degrees C to drive off the last water and any bicarbonate, and it must then be kept from the air, because it takes up both moisture and carbon dioxide readily. A sample weighed straight from a bottle left open reads high in mass and low in assay. The standard specifies the requirements, the drying conditions, the assay and the certification of the primary standard grade.

Document preview — GB 10735-2008

National Standard of the People's Republic of China

ICS: 71.040.30
Classification: G61

Issued by: General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China; Standardization Administration of China

1 Scope
2 Normative references
3 Characters
4 Specification
5 Test
5.3 Content
5.3.2.4 Coulomb constant current device diagram (see Figure 1). 1
5.3.3 Determination
5.3.4 Calculation
6 Inspection rules
7 Packaging and marking
Appendix A
Appendix B

Foreword

The standard Chapter 4 5.3.3,

5.3.4.1 are mandatory, other provisions are recommended. This standard replaces GB 10735-1989 "first reference reagent (capacity) of anhydrous sodium carbonate," compared with GB 10735-1989, the major change Of the following.

--- Standard name changed to "first reference reagent anhydrous sodium carbonate";

--- Increasing the normative references (1989 edition Chapter 2, Section 2 of this edition);

--- Modify the description of the determination of the principles of the (1989 version 4.1.1, this version 5.3.1);

--- Modify the constant current coulometric apparatus diagram (1989 version 4.1.3.4, this edition 5.3.2.4);

--- Perfect pre-titration method (the 1989 edition of 4.1.4.2, this edition 5.3.3.3);

--- Modified after introducing nitrogen loading conditions (1989 version 4.1.4.3, this edition 5.3.3.4);

--- Modify the inspection rules (1989 edition Chapter 5, Chapter 6 of this edition);

--- Increasing the content of the calculation method of Uncertainty (Excerpts Appendix B) was measured;

--- Canceled Appendix B, Appendix C (1989 edition Appendix B, Appendix C). This standard appendix A normative appendix, Appendix B is an informative annex. The standard proposed by China Petroleum and Chemical Industry Association. This standard by the Chemicals Branch of the National Chemical Standardization Technical Committee. This standard is drafted by: China Institute of Metrology, Beijing Institute of Chemical reagents. The main drafters of this standard. FEI brother, Wu Bing, Han Baoying, strong Jing Lin. This standard replaces the standards previously issued as follows:

--- GB 10735-1989. The first reference reagent anhydrous sodium carbonate Molecular formula. Na2CO

3 Molecular Weight. 105.9886 (according to 2005 international relative atomic mass).

1 Scope

a) high-precision timing constant current source. stability is better than one hundred thousandth of the dynamic characteristics of a good steady flow DC power supply, with 1.0186 × 1.0186 × 10mA and 100mA two output current, the current value is determined by the compensation method; the minimum timing resolution 0.1ms, electricity Flow and timing synchronization is less than 0.1ms.

b) temperature control standard battery pack. should meet the requirements of JJG153. Range 1V, annual variation of less than 5µV.

c) Standard resistance. should meet the requirements JJG116 of. Relative uncertainty is generally not more than 3 × 10-6.

d) direct radiation galvanometer. resistance < 100Omega, critical external resistance < 1000Omega, dividing the value of < 3 × 10-9A.

5.3.2.5 electrolytic cell apparatus (see Figure 2). An anode compartment (left) and a cathode chamber (right side) is made of quartz glass with a diameter of 50mm, 125mm high cylindrical. With between two chambers Diameter 20mm, length 80mm quartz glass tube level connections in the tube melting inside back cover sheet respectively No. 2,2,3 glass sand core, thus formed Two intermediate chambers each with a branch of the piston, and the pressure by pumping nitrogen gas pressurization method the electrolyte solution out of the intermediate chamber. Two small rooms The distance between the sand core distance 20mm, two large chamber between the sand core is 40mm. Tight pre-treated with a good white port on the anode chamber A rubber plug, the plug is inserted through a glass electrode 2, respectively, a saturated calomel electrode 3, 4 nitrogen inlet, nitrogen outlet pipe 5, a surface area of about 60cm2 platinum mesh anodes 6, the bottom of the anode compartment has a 20mm long was stirred in a sealed Teflon tube about the magnet 9, a polyethylene cover 10 placed in a platinum mesh anode on top. A cathode chamber having a 50mm × 75mm copper as the cathode 8, the bottom agar casting a rubber stopper 7. Electrolytic cell unit on magnetic stirrer workbench.

Note. Preparation of agar rubber stopper Weigh agar 3g, was added 50mL of water, boiling, etc. is added a solution of sodium sulfate (1mol/L) Volume boiled, mixed, cast in the hot cathode chamber bottom. 1

--- white rubber plug; 2

--- glass electrode; 3

--- saturated calomel electrode; 4

--- nitrogen inlet; 5

--- nitrogen outlet pipe; 6

--- platinum mesh anode; 7

--- agar stopper; 8

--- copper cathode; . 9

2 Normative references

The following documents contain provisions which, through reference in this standard and become the standard terms. For dated references, subsequent Amendments (not including errata content) or revisions do not apply to this standard, however, encourage the parties to the agreement are based on research Whether the latest versions of these documents. For undated reference documents, the latest versions apply to this standard.

GB/T 602 Determination of impurities in chemical reagents prepared standard solution ( GB/T 602-2002,

ISO 6353-1. 1982, NEQ) with

GB/T 603 chemical reagent test method Preparations of articles ( GB/T 603-2002,

ISO 6353-1 with. 1982, NEQ)

GB/T 609 chemical reagent - General method for determination of total nitrogen ( GB/T 609-2006, ISO 6353-1. 1982, NEQ)

GB/T 6682 analytical laboratory use specifications and test methods ( GB/T 6682-2008, ISO 3696. 1987, MOD)

GB/T 9723-2007 Chemicals flame atomic absorption spectrometry General

GB/T 9728 General method for determination of chemical reagents sulfate ( GB/T 9728-2007, ISO 6353-1. 1982, NEQ)

GB/T 9729 General method for determination of chloride Chemicals ( GB/T 9729-2007, ISO 6353-1. 1982, NEQ)

GB/T 9734-2008 Determination of aluminum Chemicals general method ( ISO 6353-1. 1982, NEQ)

GB/T 9738 Chemicals water insoluble determination General method ( GB/T 9738-2008, ISO 6353-1. 1982, NEQ)

GB/T 9739 General method for determination of iron chemical reagents ( GB/T 9739-2006, ISO 6353-1. 1982, NEQ)

GB 15346 chemical reagent packaging and marking

3 Characters

This reagent as a white powder, water is exposed to air gradually become a hydrate, soluble in water, soluble in ethanol.

4 Specification

Anhydrous sodium carbonate as shown in Table 1. Table

1 Name the first reference Content (Na2CO3), /% 99.98 ~ 100.02 Clarity test/number <=

5 Test

5.1 Warning Reagents used in this test method are toxic or corrosive, some of the testing process can lead to dangerous situations, the operator should take Appropriate safety and health practices.

5.2 General Provisions Unless specified otherwise in this chapter, the use of reagent purity should be more analytical, standard solution, preparations and products, according to GB/T 602, GB/T 603 provisions of preparation, test water should be consistent with GB/T 6682 specifications in two water samples according to precise weighing 0.01g, used Solution "%" are represented by the mass fraction. High purity nitrogen gas should be used.

5.3 Content

5.3.1 Principle of the method Coulomb analysis is performed by measuring a quantitative analysis of material from one electrode reaction, or a substance to be analyzed and the electrode reaction Charge (coulombs) chemical reaction product was quantitatively consumed to quantitative analysis. Coulometry principle is based on the law Where. Molar mass M

--- material in units of grams per mole (g/mol);

--- Like the number of electron transfer; F

--- Faraday constant ampere seconds per mole of (A · s/mol); I

--- the current solution by electrolysis, in amperes (A); Constant current precision coulometric titration method is based on a constant current through the electrolytic cell, so that the working electrode electrolysis to produce a titrant with cell The test substance quantitative reaction, electrochemical method to indicate the end of the reaction, the consumption of electricity by electrolysis calculated according to Faraday's law The amount of titrant to calculate the content of the test substance. This method uses a platinum mesh electrode (surface area 60cm2) as the anode using the anode 4OH- -4e 2H2O + O2 up Determination of electrode reaction of anhydrous sodium carbonate, indicating the end of the reaction with a pH meter.

5.3.2 instruments and devices

5.3.2.1 pH meter. meet JJG119-2005 Chapter 4 "0.001" requirements.

5.3.2.2 Weight. meet JJG99 verification requirements. G group, the annual variation of less than 10µg; mg group, the annual variation of less than 4µg.

5.3.2.3 heated fuel tank. temperature control accuracy of ± 0.01 °C.

5.3.2.4 Coulomb constant current device diagram (see Figure 1). 1

--- high precision timing constant current source; 2

--- electrolytic cell; 4

--- end indicator (pH meter); 5

--- dummy load resistor; 6

--- Standard resistance; 7

--- galvanometer; 8

--- temperature standard battery pack; . 9

--- step switch; 10

--- heated fuel tank. Figure

5.3.3 Determination

5.3.3.1 Preparation of formulations Weighed 322.2g sodium sulfate (Na2SO4 · 10H2O) (excellent pure), was dissolved in water and diluted to 1000mL. Weigh 79.8g copper sulfate pentahydrate, soluble in water, dilute to 1000mL.

5.3.3.2 said sample The sample was placed in a platinum crucible at (270 ± 10) °C drying 4h, cooled to room temperature in a desiccator. PTFE sample is placed in a small cup, weighing alternative method to the nearest 0.00001g. The quality of the sample shall be corrected for buoyancy, Correction method in Appendix A.

5.3.3.3 Pre-titration Cathode chamber 100mL copper sulfate solution [0.5mol/L], the anode compartment was added 1.8g of recrystallized sodium sulfate, dissolved in 130mL carbon dioxide-free water. Stirring the liquid from the manifold to the anode-high purity nitrogen 40min, removal of dissolved carbon dioxide, glass insert Glass electrode and a saturated calomel electrode. Adjust the nitrogen intake pipe into the air, maintaining a small nitrogen flow, the anode compartment electrolyte solution on the surface Maintain a high purity nitrogen atmosphere. Open the piston 1 and the piston 2, so that the anode compartment electrolyte solution flows into the middle chamber of about 2mm deep in 10.186mA electricity Shed, changing the polarity of the electrodes, an electrolyte solution pretreatment. Thereafter, 10.186mA current, incremental method for pre-titration curve, After the completion of the pre-titration, the method of pressurizing and depressurizing with intermediate washing chamber several times, and washing the inner wall of the electrolytic cell with an electrolyte solution and finally the intermediate chamber The electrolytic solution was returned to 2mm deep, the pH of the final record, the pre-titration curves plotted (see FIG. 3). The figure is the titration end point C, A Point represents the electrolysis stop time, B point represents the final pH after completion of washing solution. More than titration end portion of the charge amount should be credited The total charge amount. Remove the glass electrode and a saturated calomel electrode, with a teflon stopper stuffed respective two holes. Figure 3 pre-titration curve

5.3.3.4 titration end point and seek In order to open the piston 1 and the piston 2, so that the cathode chamber by vacuum intermediate chamber filled with electrolyte solution, close the piston 1 and the piston 2, nitrogen Adjusted to a smaller flow rate, above the surface to blow through the intake manifold, the anode chamber to maintain a positive pressure to prevent air from entering. We will even say good sample Put together with a small cup of pre-titration of the electrolyte solution in the anode chamber, the solution was stirred. Stirring was stopped, the dummy load resistor adjusts the current value 101.86mA, connected to two electrodes, start electrolysis. During electrolysis, every 15min observe the primary current value, if any changes tune Section. When the desired length of time longer than 2s when electrolysis sample purity of 100%, the electrolysis is stopped, write down the time of electrolysis. The anode chamber electrolyte solution was transferred to flat-bottomed quartz flask, chamber solution blown back anode chamber, drawing the dissolved polyethylene dropper Polyethylene cover and rubberized mesh and washed repeatedly with platinum plugs on the washing liquid was transferred to the above flat-bottomed flask. The solution was blown back into the big room Anode chamber, after the above washing method, the above-described washing solution and transferred to a flat-bottomed flask, boiled together 10min, carbon dioxide was removed, to be dissolved It was cooled to room temperature, and transferred back to the electrolytic cell anode compartment, through high purity nitrogen 40min. In 10.186mA current, incremental method to draw the end of the curve. Platinum mesh as the cathode and anode copper, each through a certain power, Hutchison Changes recorded pH value until the checkered flag after a few do. With pre-titration as repeatedly washing the sand core connecting tube, the anode chamber wall FIG point C is the titration end point, A point represents electrolysis stop time, B point represents the completion of the final pH value of the washing solution. Figure 4 endpoint titration curve

5.3.4 Calculation

5.3.4.1 Calculation of the mass fraction of anhydrous sodium carbonate Anhydrous sodium carbonate content and its value is "%" means, according to equation (2). = QPQT × 100 = I (2) Where.

--- The QP electrolytic sample charge amount actually consumed by the coulombs (the C); Theoretical amount of charge required for electrolysis of the QT

--- sample, in units of coulombs (the C); I

--- the current solution by electrolysis, in amperes (A);

--- The M values of the molar mass of anhydrous sodium carbonate units of grams per mole (g/mol);

--- Like the number of electron transfer; F

--- Faraday constant ampere seconds per mole of (A · s/mol); E

--- standard electromotive force in volts (V); R

--- standard resistor in ohms (Omega). (2) In the formula. I1

--- large current electrolysis current value in units of milliamperes (mA); I2

--- pre-titration end point and seek current value, in milliamperes (mA); Uncertainty and assay results of calculation

5.3.4.2 Expanded uncertainty assay results should generally be less than 0.02% (k = 2), the calculation method, see Appendix B.

5.4 Clarity test Clarity Standard No.

2 Weigh 5g sample was dissolved in 100mL of water, turbidity is not greater than HG/T 3484 stipulated.

6 Inspection rules

For mass-produced products, in accordance with the requirements of uniformity JJG1006 initial inspection. Bulk product inspection can be carried out by the preliminary dispensing, after extracting a sample formal test. Official test sample rule. when the total number of units is less than 200, the number of shape extraction unit less than 11; When the whole is greater than the number of units 200 When less than 500, like less than 12; when the total number of more than 500 units, like no less than 15.

7 Packaging and marking

According to GB 15346 requirements for packaging, storage and transportation, and flags are given, including. Packing unit. Class 3; Inner packaging. NB-4, NB-5, NB-6; Packaging forms. The specifications for the 600g/m2 of box board paper box, outer mounted electro-optical blue paper.

Appendix A

(Normative) Substance was weighed mass air buoyancy correction Where. rhoK

--- when the density of the air weighing in grams per cubic centimeter (g/cm 3); rhoW

--- density of the material to be weighed in grams per cubic centimeter (g/cm 3); pf

--- weights density in grams per cubic centimeter (g/cm 3). Formula (A.1) in. Air density (rhoK), in grams per cubic centimeter (g/cm 3), according to equation (A.2) Calculated. Where. P1

--- atmospheric pressure value in units of kilopascals (kPa); P2

--- vapor pressure of water at room temperature value in units of kilopascals (kPa); (A.2) in the formula. The value of water vapor pressure (P2), in units of kilopascals (kPa), according to equation (A.3) Calculated. P2 = W × P3 (A.3) Where. W

--- values of relative humidity of air in%; Numerical P3

--- saturated vapor pressure of water at room temperature, measured in kilopascals (kPa). Water vapor pressure values are shown in Table A. 1. Table A.

Appendix B

(Informative) Calculation Determination of Uncertainty B. Calculate 1 assay results of the Class A standard uncertainty components A class standard uncertainty component [u A (Qin)] according to formula (B.1) Calculated. U A (Qin) = Ju (Qin) like (B.1) Where. Standard deviation Ju (Qin)

--- like second measurement results, the value of "%" means. B. Calculation 2 assay results of Class B combined standard uncertainty components Class B according to the relative combined standard uncertainty component assay results Chapter 5 (2) of [u cBrel (Qin)] according to formula (B.2) Calculated. Where. U rel (I)

--- current relative standard uncertainty component; The relative standard u rel (M)

--- anhydrous sodium carbonate molar mass values of the uncertainty components; U rel (F) and the relative standard

--- Faraday constant uncertainty components; U rel (x)

--- determine the end point of the relative standard uncertainty component. B.

2.1 Current relative standard uncertainty component computing Current relative standard uncertainty component [u...

......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 30 pages — is available in the English PDF.

Referenced standards

Normative references

ISO 6353 · GB/T 609-2006 · ISO 3696 · GB/T 9728-2007 · GB/T 9729-2007 · GB/T 9734-2008 · GB/T 9738-2008 · GB/T 9739-2006 · HG/T 3484

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