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GB 10731-2008 English PDF

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GB 10731-2008: Primary chemical -- Potassium dichromate
Status: Valid

GB 10731: Evolution and historical versions

Standard IDContents [version]USDSTEP2[PDF] delivered inStandard Title (Description)StatusPDF
GB 10731-2008English399 Add to Cart 3 days [Need to translate] Primary chemical -- Potassium dichromate Valid GB 10731-2008
GB 10731-1989English359 Add to Cart 3 days [Need to translate] Primary chemical--Potassium dichromate Obsolete GB 10731-1989

PDF similar to GB 10731-2008


Standard similar to GB 10731-2008

GB/T 9722   HG/T 3489   GB/T 9741   GB 10732   GB 10733   GB 10730   

Basic data

Standard ID GB 10731-2008 (GB10731-2008)
Description (Translated English) Primary chemical -- Potassium dichromate
Sector / Industry National Standard
Classification of Chinese Standard G61
Classification of International Standard 71.040.30
Word Count Estimation 17,163
Date of Issue 2008-06-18
Date of Implementation 2009-06-01
Older Standard (superseded by this standard) GB 10731-1989
Regulation (derived from) Announcement of Newly Approved National Standards No. 10 of 2008 (total 123)
Issuing agency(ies) General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, Standardization Administration of the People's Republic of China
Summary This Chinese standard specifies the first reference reagent potassium dichromate traits, specifications, testing, inspection and marking and packaging rules. This standard applies to the first benchmark test reagent potassium dichromate.

GB 10731-2008: Primary chemical -- Potassium dichromate

---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Primary chemical.Potassium dichromate ICS 71.040.30 G61 National Standards of People's Republic of China Replacing GB 10731-1989 The first reference reagent potassium dichromate Posted 2008-06-18 2009-06-01 implementation Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China Standardization Administration of China released

Foreword

The standard Chapter 4 5.2.3,5.2.4.1 are mandatory, other provisions are recommended. This standard replaces GB 10732-1989 "first reference reagent (capacity) of potassium dichromate," Compared with GB 10732-1989, the main changes as follows. --- Standard name changed to "first reference reagent potassium dichromate"; --- 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 5.2.1); --- Modified Coulomb constant current device diagram (1989 version 4.1.3.4, this edition 5.2.2.3); --- 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 10731-1989. The first reference reagent potassium dichromate Warning. some of the test procedure specified in this standard can lead to dangerous situations, the user has the responsibility to take appropriate safety and health practices. Molecular formula. K2Cr2O7 Molecular Weight. 294.185 (according to 2005 international relative atomic mass).

1 Scope

This standard specifies the first reference reagent potassium dichromate traits, specifications, testing, inspection rules, packaging and marking. This standard applies to the first reference reagent potassium dichromate test.

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 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 9738 Chemicals water insoluble determination General method (GB/T 9738-2008, ISO 6353-1. 1982, NEQ) GB 15258 rules for preparation of chemical safety labels GB 15346 chemical reagent packaging and marking JJG99 weight JJG116 standard resistor JJG153 standard battery JJG1006 a standard material specification

3 Characters

This reagent is orange-red crystalline particles or powder, soluble in water, soluble in ethanol.

4 Specification

Potassium dichromate as shown in Table 1. Table 1 Name the first reference Content (K2Cr2O7), /% 99.98 ~ 100.02 Water-insoluble, /% ≤0.003 Chloride (Cl), /% ≤0.001 Sulphate (SO4), /% ≤0.003 Table 1 (continued) Name the first reference Sodium (Na), /% ≤0.01 Calcium (Ca), /% ≤0.001 Iron (Fe), /% ≤0.001

5 Test

5.1 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. 5.2 Content 5.2.1 The 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 constant current at the platinum cathode produced by electrolysis of ferrous ions to be measured dichromate reaction of potassium dichromate content. 5.2.2 instruments and devices 5.2.2.1 Weight. meet JJG99 verification requirements. G group, the annual variation of less than 10μg; mg group, the annual variation of less than 4μg. 5.2.2.2 heated fuel tank. temperature control accuracy of ± 0.01 ℃. 5.2.2.3 Coulomb constant current device diagram (see Figure 1). 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, current Timing and synchronization of 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 < 100Ω, critical external resistance < 1000Ω, dividing the value of < 3 × 10-9A/indexing. 1 --- high precision timing constant current source; 2 --- 7½-Meter; 3 --- electrolytic cell; 4 --- end indicator (galvanometer); 5 --- dummy load resistor; 6 --- Standard resistance; 7 --- galvanometer; 8 --- temperature standard battery pack; . 9 --- step switch; 10 --- heated fuel tank. Figure 1 Schematic diagram of the constant current coulometric 5.2.2.4 end indication circuit (see FIG. 2). Platinum electrode as the indicator electrode, a saturated calomel electrode as the reference electrode, the voltage between the two electrodes is 0.85V. Figure 2 indicates the end of the circuit 5.2.2.5 electrolytic cell apparatus (see Figure 3). A cathode compartment (left) and an anode compartment (right) is a diameter of 50mm, 125mm high cylinder 95 made of glass material. With between two chambers Diameter 20mm, glass horizontal length 80mm connections in the tube melting inside back cover sheet respectively No. 2,2,3 glass sand core, thereby forming two Have an intermediate chamber manifold with the piston, and the pressure by pumping nitrogen gas pressurization method the electrolyte solution out of the intermediate chamber. Small room two sand core The distance between the distance 20mm, two large chamber between the sand core is 40mm. The cathode chamber mouth tight with a good pre-treated white rubber A plug, the plug is inserted through the working electrode 2 are platinum, platinum bis indicator electrode, saturated calomel electrode 4, 5 nitrogen inlet, nitrogen outlet pipe 6, The bottom of the cathode compartment 20mm long was stirred in a sealed Teflon tube about the magnet 8, an anode chamber having a platinum working electrode 10, The bottom of a cast silicone gel plug 9. Electrolytic cell unit on magnetic stirrer workbench. 1 --- white rubber plug; 2 --- platinum working electrode; 3 --- double platinum indicator electrode; 4 --- saturated calomel electrode; 5 --- nitrogen inlet; 6 --- nitrogen outlet pipe; 7 --- sample hole; 8 --- stirring; --- Silica gel plug. 9; 10 --- platinum working electrode; . 11 --- piston 1; 12 --- piston 2. 3 cell apparatus of FIG. 5.2.3 Determination 5.2.3.1 Preparation of formulations 111mL amount of sulfuric acid slowly into about 700mL of water, cooled and diluted to 1000mL. 5.2.3.1.2 electrolyte solution He weighed 192.9g ferric (Ⅲ) ammonium, dissolved in a small amount of sulfuric acid solution [2mol/L], and then sulfuric acid solution [2mol/L] diluted to 1000mL, if necessary, by the sand core funnel. 5.2.3.1.3 ferrous sulfate solution Weigh ferrous sulfate 10g, dissolved in 100mL sulfuric acid solution [2mol/L] in. Weigh 2.94g work reference reagent potassium dichromate, dissolved in water and diluted to 1000mL. 5.2.3.2 Test preparation 5.2.3.2.1 cell cleaning Before use lotion soak a while and then with water repeatedly washed the new cell and evacuated to wash the sand core colorless and then with water repeatedly pumping washed several times spare. Good cleaning electrolytic cell can be used repeatedly, just after the experiment of removing solution, repeatedly washed several times with water pumping and water full backup. 5.2.3.2.2 formulated silicone gel plug Weigh 12.5g of sodium silicate, placed in 150mL beaker, add 50mL water dissolved, add 20mL sulfuric acid solution [2mol/L], stirring was And uniform boiling, After cooling the solution was poured into the anode compartment of the electrolytic cell (right side), in the sulfuric acid solution was gradually added with slow stirring [2mol/L] to dissolve Become muddy liquid, gel. Formulated silicone gel stuffed add a little sulfuric acid solution [2mol/L] kept moist. Regeneration 5.2.3.2.3 platinum working electrode and a double platinum indicator electrode The front electrode in nitric acid before each use, after ferrous sulfate solution soak regeneration, usually every 10min to soak. 5.2.3.2.4 high purity nitrogen purge Commercially available high-purity nitrogen in sequence over 401 high-efficiency oxygen scavenger [residual oxygen (10 × 10-9)] and a bottle of electrolyte solution and the cathode chamber containing a bottle Water scrubber, after connecting the electrolytic cell. 5.2.3.3 said sample The samples were placed in open glass, dried at 130 ℃ 6h, cooled to room temperature in a desiccator. The sample is placed in polyethylene plastic cuvette, alternative method, were weighed to the nearest 0.00001g. Sample mass for buoyancy correction shall Positive correction method given in Appendix A. Pretreatment 5.2.3.4 electrolyte solution Since the electrolyte solution contains certain oxidizable and reducible impurities must be repeated using electrolytic reduction and electrolytic oxidation before the experiment deal with. The specific approach is to join 150mL electrolyte solution in the cathode compartment (left), and with a 100mA current to electrolytic reduction 500s, then Transform electrode polarity electrolytic oxidation 500s, so repeated three times. Each electrode polarity of the electrodes before converting the need for regeneration. Adding an appropriate amount dichromate Solution of potassium [0.01mol/L] solution in excess of ferrous (Fe2 +) is reacted with, bringing them closer to the equivalence point, stirring, pass from the manifold to the solution 1h into the high-purity nitrogen to remove dissolved oxygen. 5.2.3.5 Pre-titration Open the piston introduction about 2mm deep layer of the electrolyte solution to the intermediate chamber, adding an appropriate amount of potassium dichromate solution [0.01mol/L] in the cathode chamber At the end of the electrolyte solution prior to incremental 10.186mA current law, platinum - at calomel electrode potential of 0.85V seek painted titration song line. After the pre-titration with compression and decompression method of cleaning the intermediate chamber several times, with an electrolyte electrolytic cell inner wall of the washing solution, and finally to make the Electrolyte solution compartment restored to 2mm deep, final instructions to record the current value. More than titration end portion of the total amount of electric charge should be included The amount of the charge. 5.2.3.6 titration end point and seek Open the piston, so that the middle chamber filled with electrolyte solution, close the piston, to blow through nitrogen inlet above the liquid surface, the cathode chamber is maintained positive Pressure to prevent air from entering. By adjusting the current to the dummy load 101.86mA, connect the electrodes to start electrolysis. During electrolysis, 15min Once observed about the current subject to changes in regulation. Electrolysis to titrate a sample equivalent to 99.9% needed to stop ferrous ions electrolysis. Write down the time to calculate the amount of charge consumed. Open the sample hole in the lid, put in a sample of known mass from the hole, the solution was stirred until To sample is completely dissolved, the solution was bright green. In order to recover the diffusion into the intermediate chamber during electrolysis a small amount of ferrous ions, washed with the aforementioned method for pressurizing and depressurizing the electrolyte solution Compartment several times. After the pre-titration step and draw the same curve with the end of the incremental method 10.186mA current washed again intermediate chamber several times until the power Current value unchanged, and the record indicates current value. The recording of the current directions - electrolysis time data, draw the end of the titration curve. typical The end of the curve shown in Figure 4.

4 a schematic diagram of the end of the curve

Fig. A point represents a current value when the electrolysis was stopped, B point represents a current value after completion of washing, two curves cross the linear portion extension line Point C is the endpoint of the titration. Figure 4 is calculated from the amount of charge before it reaches the end of consumption and spread to the intermediate chamber of Fe2 + ions required for charge Amount, namely A, B the amount of charge between two points. End of an electrolyte solution was measured after the sample may continue to titrate the second and third parts of the sample. 5.2.4 Calculation 5.2.4.1 Calculation of the mass fraction of potassium dichromate The mass fraction of potassium dichromate, the value in the "%" means, according to equation (2). QP QT × 100 = I Shaped · M · F × 100 = (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); M --- molar mass of potassium dichromate value, 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); E --- standard electromotive force in volts (V); R --- standard resistor in ohms (Ω). (2) In the formula. Where. 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 5.2.4.2 Expanded uncertainty assay results should generally be less than 0.02% (k = 2), the calculation method, see Appendix B. 5.3 Water insoluble matter Weigh 50g sample was dissolved in 450mL hot water in the water bath for 1h after, according to the provisions of GB/T 9738 Determination. 5.4 Chloride 5.4.1 Preparation of chloride-free potassium dichromate solution 10g samples were weighed, dissolved in 140mL of water (25%) was added 100mL nitric acid solution was heated to 50 ℃. Add 10mL silver nitrate solution Solution (17g/L), diluted to 300mL, shake, place 12h ~ 18h, with a No. 4 glass filter crucible filtration. 5.4.2 Determination Weigh 1g sample was dissolved in 20mL of water added 10mL solution of nitric acid (25%), was heated to 50 ℃, add 1mL silver nitrate solution (17g/L), shake for 10min. The turbidity of the solution was not greater than the standard turbidity solution. Standard preparation turbid solution is to take the ratio of 0.01mg containing chloride (Cl) and 30mL standard solution chloride-free potassium dichromate solution Was heated to 50 ℃, the sample solution was placed 10min Meanwhile, turbidity. 5.5 sulfate Preparation 5.5.1 Test Solution A Weigh 1g sample was dissolved in 10mL of water, add 13mL hydrochloric acid solution (20%), with a 20mL tributyl phosphate extraction, intense shaking 1min, place stratification, water phase, and then 20mL tributyl phosphate extraction was repeated, then repeated with 5mL ether aqueous phase was extracted twice with water Phase diluted to 30mL. 5.5.2 Determination Measure 15mL test solution A, evaporated on a water bath. The residue was dissolved in water (filtered if necessary), was diluted to 20mL, 0.5mL add salt Acid solution (20%), according to the provisions of GB/T 9728 Determination. The turbidity of the solution was not greater than the standard turbidity solution. Standard preparation turbid solution is to take the ratio of 0.015mg containing sulfate (SO4) standard solution was diluted to 20mL, and with the same volume of test solution When the same treatment. 5.6 Sodium Determined according to the provisions of GB/T 9723-2007 of. 5.6.1 Instrument Conditions Source. sodium hollow cathode lamp; Wavelength. 589.0nm; Flame. acetylene - air. 5.6.2 Determination Weigh 2g sample was dissolved in water and diluted to 100mL. Take 10mL, a total of four parts, according to the provisions of GB/T 9723-2007 in 7.2.2 Measurement results calculated according to the provisions of 7.2.3. 5.7 calcium Measure 6mL test solution A (5.5.1), place the evaporating dish, evaporated on a water bath. The residue was dissolved in water, diluted to 10mL, plus 10mL "Ethanol (95%)", 0.5mL 1mL mixed alkali and glyoxal bis aminophenol ethanol solution (2g/L), shake for 5min, With 5mL chloroform extraction (temperature does not exceed 30 ℃), colorimetric immediately. The organic phase was red can not be deeper than the standard colorimetric solution. Preparation of the standard developing solution containing 0.002mg is to take the ratio of calcium (Ca) standard solution was diluted to 10mL, and at the same time with the same volume of test solution deal with. 5.8 iron Weigh 0.2g sample was dissolved in 10mL water, add 1.5mL hydrochloric acid solution (20%), 5mL "Ethanol (95%)", 1mL "30% over Hydrogen peroxide "and 1 drop of sulfuric acid on the steam bath to near dryness. The residue was dissolved in water and diluted to 20mL, adjust solution with sodium acetate solution (250g/L) pH value of the solution to 4, diluted to 25mL, add 2mL hydroxylamine chloride solution (100g/L), shake for 5min. Plus 1mL4,7- diphenyl 1,10-phenanthrene group  morpholino solution Ba {[(C6H5) 2C12H6N2] = 0.001mol/L}, shake, with 10mL isoamyl alcohol extraction. The organic phase was Red shall not be deeper than the standard colorimetric solution. Preparation of the standard solution is to take the colorimetric containing 0.002mg of iron (Fe) standard solution, the same treatment simultaneously with the sample.

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 is less than 500, like less than 12; when the total number of units greater than 500, 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; Tags. compliance with the provisions of GB 15258, marked "oxidant."

Appendix A

(Normative) Substance was weighed mass air buoyancy correction ρW -1 Where. ρK --- when the density of the air weighing in grams per cubic centimeter (g/cm 3); ρW --- 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 (ρK), in grams per cubic centimeter (g/cm 3), according to equation (A.2) Calculated. ρK = 0.00129 273.15 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. 1 Water vapor pressure (P Rao k) Temperature (C °) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 11 1.312 1.321 1.329 1.338 1.347 1.356 1.365 1.374 1.383 1.392 12 1.402 1.411 1.420 1.430 1.439 1.448 1.458 1.468 1.477 1.487 13 1.497 1.507 1.516 1.526 1.536 1.546 1.556 1.567 1.577 1.587 14 1.598 1.608 1.618 1.629 1.639 1.650 1.661 1.672 1.682 1.693 15 1.704 1.715 1.726 1.737 1.749 1.760 1.771 1.783 1.794 1.806 16 1.817 1.829 1.840 1.852 1.864 1.876 1.888 1.900 1.912 1.924 17 1.937 1.949 1.961 1.974 1.986 1.999 2.011 2.024 2.037 2.050 18 2.063 2.076 2.089 2.102 2.115 2.129 2.142 2.155 2.169 2.183 19 2.196 2.210 2.224 2.238 2.252 2.266 2.280 2.294 2.308 2.323 20 2.337 2.352 2.366 2.381 2.396 2.410 2.425 2.440 2.455 2.471 Table A. 1 (cont.) Temperature (C °) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 21 2.486 2.501 2.517 2.532 2.548 2.563 2.579 2.595 2.611 2.627 22 2.643 2.659 2.675 2.692 2.708 2.724 2.741 2.758 2.775 2.791 23 2.808 2.825 2.843 2.860 2.877 2.894 2.912 2.930 2.947 2.965 44 9.103 9.150 9.198 9.245 9.293 9.341 9.390 9.438 9.487 9.536

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 (-)] according to formula (C.1) Calculated. U A (-) = Ju (-) 槡 like (B.1) Where. Ju (-) --- times the standard deviation of shape measurement result, the value of "%" means. B. Calculation 2 assay results of Class B combined standard uncertainty components The measurement results in accordance with Chapter 5 (2) Class B content relative combined standard uncertainty component [u cBrel (-)] according to equation (C.2) Calculated. Where. U rel (I) --- current relative standard uncertainty component; The relative standard u rel (M) --- potassium dichromate 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 rel (I)] according to equation (C.3) Calculated. U rel (I) = U (I) (B.3) Where. U (I) --- current standard uncertainty component, in amperes (A); I --- the current value, the standard battery voltage value divided by the standard resistance values obtained in amperes (A). Formula (B.3) in. U (I) I = + U (Vp) [] Vp + U (R) [] R Sang (B.4) Where. U (Vp) --- standard voltage battery pack temperature standard uncertainty components, in volts (V); --- Temperature value Vp standard battery voltage in volts (...

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