1、BRITISH STANDARD BS 4427-2: 1969 Methods of test for Sodium tripolyphosphate (pentaSodium triphosphate) and sodium pyrophosphate (tetraSodium pyrophosphate) Part 2: Measurement of pH value of sodium tripolyphosphateBS4427-2:1969 This British Standard, having been approved by the ChemicalsIndustry St
2、andards Committee, was published underthe authority of the Executive Board on 28February1969 BSI 11-1999 The following BSI reference relates to the work on this standard: Committee reference CIC/25 ISBN 580 05386 5 Co-operating organizations The Chemicals Industry Standards Committee, under whose au
3、thority this British Standard was prepared, consists of representatives from the following Government departments and scientific and industrial organizations: Board of Trade British Steel Industry Chemical Industries Association* Department of Health & Social Security Fertiliser Manufacturers Associ
4、ation Ltd.* Gas Council Institution of Gas Engineers Ministry of Technology. Laboratory of the Government Chemist* National Sulphuric Acid Association Royal Institute of Public Health & Hygiene The industrial organizations marked with an asterisk in the above list, together with the following, were
5、directly represented on the committee entrusted with the formulation of the UnitedKingdom point of view in the international work leading to the publication of this British Standard: British Pharmacopoeia Commission Flour Milling and Baking Research Association Institute of Metal Finishing National
6、Association of Soft Drink Manufacturers Society for Water Treatment and Examination Textile Institute Amendments issued since publication Amd. No. Date CommentsBS4427-2:1969 BSI 11-1999 i Contents Page Co-operating organizations Inside front cover Foreword ii 1 Scope 1 2 Principle 1 3 Reagents 1 4 A
7、pparatus 1 5 Procedure 1 6 Expression of results 1 7 Test report 1BS4427-2:1969 ii BSI 11-1999 Foreword For some years the UnitedKingdom has participated in the work of preparing methods of test for sodium tripolyphosphate and sodium pyrophosphate for industrial use, carried out within Working Group
8、7of Technical Committee47 Chemistry, of the International Organization for Standardization (ISO). As international agreement is reached on the methods, it is proposed to publish them as parts of this British Standard. This part is technically identical with ISO Recommendation R851, “Sodium tripolyph
9、osphate for industrial use. Measurement of pH. Potentiometric method.” A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer imm
10、unity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, pages1 and 2, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in th
11、e amendment table on the inside front cover.BS4427-2:1969 BSI 11-1999 1 1 Scope This Part of BS 4427 describes a potentiometric method for the measurement of the pH value of a solution at a conventional concentration of10g/l, of sodium tripolyphosphate for industrial use. 2 Principle The principle o
12、f this method of test is the measurement of the pH of a sodium tripolyphosphate solution at a conventional concentration of10g/l by means of a pH meter fitted with a glass electrode. 3 Reagents Freshly boiled and cooled distilled water shall be used in the test. The following reagents shall be used:
13、 3.1 Sodium tetraborate buffer solution, 0.01M. Dissolve3.81 0.01g of sodium tetraborate decahydrate (Na 2 B 4 O 7 .1OH 2 O) in water and then dilute to1000ml. The solution should be stored in the absence of atmospheric carbon dioxide and renewed at least once a month. According to the temperature,
14、this solution gives the following pH values: The pH change for + 1degC is equal to 0.008pH unit. 3.2 Sodium tetraborate and sodium hydroxide buffer solution. Add 100ml of0.01N sodium hydroxide solution to100ml of the sodium tetraborate buffer solution (3.1) and mix thoroughly. According to the tempe
15、rature, this solution gives the following pH values: The pH change for + 1degC is equal to 0.006pH unit. 4 Apparatus Ordinary laboratory apparatus with the following shall be used: 4.1 pH meter, fitted with a glass electrode, sensitivity0.05pH unit. 5 Procedure 5.1 Test portion. Weigh to the nearest
16、 milligramme, 1g of the test sample. 5.2 Preparation of the sample solution. Place50ml of water in a beaker of suitable capacity(250ml, for example). Add by small quantities the test portion (5.1) and stir with a glass rod until the sample is dissolved. Transfer quantitatively the solution to a100ml
17、 one-mark volumetric flask, dilute to the mark and mix thoroughly. NOTEThis solution should be prepared just before use. 5.3 Determination. Transfer the contents of the flask to a dry beaker of suitable capacity (250ml, for example) and measure its pH value with the pH meter (4.1) previously calibra
18、ted against the buffer solution (3.1 or3.2). The buffer solution chosen should be the one with a pH value lower than that of the sample solution. The pH of the buffer solution should not be more than0.5pH unit lower than the pH of the sample solution. The pH meter calibration and the measurement of
19、the pH of the sample solution should be carried out at the same temperature. 6 Expression of results Express the results in pH units to the nearest0.05pH unit, indicating the temperature of the measurement. 7 Test report State the following in the report: 1) the reference of the method used, 2) the
20、results and the method of expression used, 3) any unusual features noted during the determination, 4) any operation not included in this standard or regarded as optional. C pH 15 9.26 20 9.22 25 9.18 30 9.14 C pH 15 9.64 20 9.61 25 9.58 30 9.552 blankBS4427-2:1969 BSI 11-1999 British Standards The f
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