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1、INTERNATIONAL STANDARD INTERNATIONAL ORGANIZATION FOR STANDARDIZATION .MEYYHAPOlRWd OPrAHM3AWX IlO CTAHAPTMJAUt4M.ORGAN,SAT,ON ,NTERNAT,ONALE DE NORMALISATION chlorate for industrial use - Determination of chlorate content - Dichromate titrimetric method Chlorate de sodium B usage industriel - Dosag
2、e du chlorate - Me thode titrime trique au dichromate First edition - 1975-02-15 iii IJDC 661.442 : 546.135 : 543.24 Ref. No. IS0 3199-1975 (E) E 7 % Descriptors : sodium chlorate, chemical analysis, determination of content. chlorates, volumetric analysis. F; 0 2 Price based on 2 pages Copyright In
3、ternational Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 22:22:10 MDTNo reproduction or networking permitted without license from IHS -,-,- FOREWORD IS0 (the International Organization for Standardiz
4、ation) is a worldwide federation of national standards institutes (IS0 Member Bodies). The work of developing International Standards is carried out through IS0 Technical Committees. Every Member Body interested in a subject for which a Technical Committee has been set up has the right to be represe
5、nted on that Committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. Draft International Standards adopted by the Technical Committees are circulated to the Member Bodies for approval before their acceptance as International Standar
6、ds by the IS0 Council. International Standard IS0 3199 was drawn up by Technical Committee ISO/TC 47, Chemistry, and circulated to the Member Bodies in September 1973. It has been approved by the Member Bodies of the following countries : Austria Belgium Bulgaria Chile Czechoslovakia France Germany
7、Hungary India Ireland Italy Netherlands New Zealand Poland Portugal Romania No Member Body expressed disapproval of the document. South Africa, Rep. of Spain Switzerland Thailand Turkey United Kingdom U.S.S.R. Yugoslavia 0 International Organization for Standardization, 1975 l Printed in Switzerland
8、 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 22:22:10 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD IS0 3199-1975 (E) Sodiu
9、m chlorate for industrial use - Determination of chlorate content - Dichromate titrimetric method 1 SCOPE AND FIELD OF APPLICATION This International Standard specifies a dichromate titrimetric method for the determination of the chlorate content of sodium chlorate for industrial use. The method is
10、not applicable to the analysis of mixtures for agricultural use such as herbicides, pesticides, etc., in which certain constituents may cause interference. 2 PRINCIPLE Reduction of the chlorate by a known quantity, in excess, of an iron salt. Titration of the excess of iron salt with a standard volu
11、metric solution of potassium dichromate in the presence of barium diphenylamine-4-sulphonate solution as indicator. 3 REAGENTS During the analysis, use only reagents of recognized analytical reagent grade and only distilled water or water of equivalent purity. 3.1 Orthophosphoric acid, p approximate
12、ly I,71 g/ml, about 85 % (m/m) solution. 3.2 Sulphuric acid, p approximately I,84 g/ml, about 96 % (m/m) solution or approximately 36 N. 3.3 Sulphuric acid, approximately 18 N solution. 3.4 Iron sulphate, approximately 0,l N solution. Weigh, to the nearest 0,Ol g, 39.2 g of ammonium iron sulphate he
13、xahydrate (NH4)2Fe(S04)2.6H20, dissolve in 500 ml of water, slowly add 40 ml of the sulphuric acid solution (3.3), cool, dilute to the mark in a 1 000 ml one-mark volumetric flask and mix. Store this solution in a glass bottle fitted with a ground glass stopper. 3.5 Potassium dichromate, 0,l N stand
14、ard volumetric solution. Weigh, to the nearest 0,000 1 g, 4,903 g of potassium dichromate, previously dried at about 200 “C for about 16 h and cooled in a desiccator. Dissolve in water, dilute to the mark in a 1 000 ml one-mark volumetric flask and mix. Store this solution in a glass bottle fitted w
15、ith a ground glass stopper. 3.6 Barium diphenylamine-4-sulphonate, 4 g/l solution. 4 APPARATUS Ordinary laboratory apparatus. 5 PROCEDURE 5.1 WARNING Sodium chlorate induces combustion. Avoid storing or handling it near a source of heat. Also avoid all contact of the product or its solutions with ac
16、ids or combustible materials (paper, cardboard, clothing, wood, rags, fatty matter, etc.) which may ignite or subsequantly form an explosive mixture. If any materials are accidentally impregnated with sodium chlorate, flush them with water. 5.2 Test portion Weigh, to the nearest 0,001 g, approximate
17、ly 3 g of the test sample. 5.3 Blank test Carry out at the same time as the determination, following the same procedure, a blank test using the same quantities of all the reagents as used for the determination but replacing the test solution (5.4) by 20 ml of water. 5.4 Preparation of test solution
18、Dissolve the test portion (5.2) in water, dilute to the mark in a 1 000 ml one-mark volumetric flask and mix. 5.5 Determination Place 20,O ml of the test solution (5.4) in a 500 ml conical flask. Add 50,O ml of the iron sulphate solution (3.4), then add slowly and carefully, with cooling, 20 ml of t
19、he sulphuric acid solution (3.2) and 5 ml of the orthophosphoric acid solution (3.1). Allow to stand for 10 min at ambient temperature. 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/
20、25/2007 22:22:10 MDTNo reproduction or networking permitted without license from IHS -,-,- Iso3199-1975 E) Dilute to approximately 300 ml, add 5 drops of the barium diphenylamine-4-sulphonate solution (3.6) and titrate with the standard volumetric potassium dichromate solution (3.5) until the colour
21、 changes to violet. 6 EXPRESSION OF RESULTS 6.1 Method of calculation The sodium chlorate (NaClOa) content, expressed as a percentage by mass, is given by the formula 0,017 75 is the mass, in grams, of sodium chlorate corresponding to 1 ml of exactly 1 N standard volumetric potassium dichromate solu
22、tion. 6.2 Repeatability and reproducibility Comparative analyses carried out in 9 laboratories by 18 operators gave the statistical information shown in the following table : Mean (% m/m) 1000 100 x o 017 75 = 8875 WI - V2) T Standard of repeatability (a,) I 0.15 (.V, -V,) x Txyx- , m m deviation of
23、 reproductibillty (CT,) / 0,31 where VI is the volume, in millilitres, of the standard volumetric potassium dichromate solution (3.5) used for the blank test; V2 is the volume, in millilitres, of the standard volumetric potassium dichromate solution (3.5) used for the determination; T is the actual
24、concentration, expressed as normality, of the standard volumetric potassium dichromate solution (3.5); m is the mass, in grams, of the test portion (5.2); 7 TEST REPORT The test report shall include the following particulars : a) the reference of the method used; b) the results and the method of exp
25、ression used; c) any unusual features noted during the deter- mination; . d) any operation not included in this International Standard, or regarded as optional. 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 22:22:10 MDTNo reproduction or networking permitted without license from IHS -,-,-