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1、BRITISH STANDARD BS 5688-1: 1979 ISO 1914:1972 Methods of test for Boric acid, boric oxide, disodium tetraborates, sodium perborates and crude sodium borates for industrial use Part 1: Determination of boric acid content of boric acid ISO title: Boric acid for industrial use Determination of boric a
2、cid content Volumetric method NOTEIt is recommended that this Part be read in conjunction with the information in the “General introduction”, published separately as BS 5688-0. UDC 661.65:546.273-32:543.062:546.273-32 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:49:29 GMT+00:00 2006, Un
3、controlled Copy, (c) BSI BS 5688-1:1979 This British Standard, having been prepared under the direction of the Chemicals Standards Committee, was published under the authority of the Executive Board on 28 February 1979 BSI 12-1999 The following BSI references relate to the work on this standard: Com
4、mittee reference CIC/16 Draft for comment 74/53496 DC ISBN 0 580 10534 2 National foreword This Part of BS 5688 is identical with ISO 1914 “Boric acid for industrial use Determination of boric acid content Volumetric method” published by the International Organization for Standardization (ISO). Term
5、inology and conventions. The text of the International Standard has been approved as suitable for publication, without deviation, as a British Standard. Some terminology and certain conventions are not identical with these used in British Standards; attention is drawn to the following. Where the wor
6、ds “International Standard” appear, referring to this standard, they should be interpreted as “British Standard”. Cross-reference. At present there is no corresponding British Standard for ISO . . . . (see clause 5). Reference should be made to BS 5309 “Methods for sampling chemical products” Part 4
7、 “Sampling of solids”. Additional information Reagents. Unless otherwise stated, it is essential that the reagents used in this determination be of recognized analytical grade. NOTEIn 3.4, the symbol for concentration by volume should be sloping, i.e. “(V/V)”. A British Standard does not purport to
8、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 immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, p
9、ages i and ii, pages 1 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 the amendment table on the inside front cover. Amendments issued since publication Amd. No.Date of issueComment
10、s Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:49:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5688-1:1979 BSI 12-1999i Contents Page National forewordInside front cover 1Scope and field of application1 2Principle1 3Reagents1 4Apparatus1 5Sampling1 6Procedure1 7Expression of results
11、1 8Test report1 Publication referred toInside back cover Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:49:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:49:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5688-1:1979 BSI 1
12、2-19991 1 Scope and field of application This International Standard specifies a volumetric method for the determination of the boric acid content of boric acid for industrial use. 2 Principle Titration of a dissolved test portion with a standard volumetric solution of sodium hydroxide in the presen
13、ce of mannitol or sorbitol, using phenolphthalein as indicator. 3 Reagents Distilled water or water of equivalent purity, free from carbon dioxide, shall be used in the test. 3.1 Mannitol, neutral, or alternatively sorbitol, neutral. These products shall satisfy the following condition: 5.0 g, disso
14、lved in 50 ml of carbon dioxide-free water, requires for neutralization not more than 0.3 ml of 0.02 N sodium hydroxide solution using phenolphthalein solution as indicator. 3.2 Hydrochloric acid, 0.25 N standard volumetric solution. 3.3 Sodium hydroxide, 0.5 N standard volumetric solution, free fro
15、m carbonate. 3.4 Phenolphthalein, 10 g/l ethanolic solution. Dissolve 1 g of phenolphthalein in 95 % (V/V) ethanol, dilute to 100 ml with the same ethanol and add 0.02 N sodium hydroxide solution until the first appearance of a pink colour. 4 Apparatus Ordinary laboratory apparatus. 5 Sampling Follo
16、w the principles described in ISO . . . .1). 6 Procedure 6.1 Test portion Weigh, to the nearest 0.001 g, about 1 g of the laboratory sample. 6.2 Determination Transfer the test portion (6.1) to a beaker and dissolve in about 120 ml of water by heating, avoiding boiling. Cool the solution to ambient
17、temperature, add approximately 15 g of the mannitol or sorbitol (3.1) and 0.4 ml of the phenolphthalein solution (3.4). Titrate the solution with the sodium hydroxide solution (3.3) to a distinct pink colour. NOTETo ensure that the correct titration end point is obtained, the following standard colo
18、ur matching solution may be used for comparison with the solution being titrated. Mix 50 ml of a 3.81 g/l solution of disodium tetraborate decahydrate (Na2 B4 O7.10H2 O), 100 ml of water, 2.0 ml of the hydrochloric acid solution (3.2), 0.4 ml of the phenolphthalein solution (3.4). Equal volumes of t
19、his solution and of the titrand shall be compared in similar beakers. 7 Expression of results Boric acid content (H3BO3) is given, as a percentage by mass, by the formula: where Vis the volume, in millilitres, of the sodium hydroxide solution (3.3) used in the titration; mis the mass, in grams, of t
20、he test portion. 8 Test report The test report shall include the following particulars: a) the reference of the method used; b) the results and the method of expression used; c) any unusual features noted during the determination; d) any operation not included in this International Standard or regar
21、ded as optional. 1) Under study. V m - -3.092 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:49:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 blank Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:49:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5688-1:1979 BSI 12-1999 Publi
22、cation referred to See national foreword. Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:49:29 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5688-1: 1979 ISO 1914:1972 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is the independent national body responsib
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