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1、BRITISH STANDARD BS 6092-11: 1981 Methods of Sampling and test for sodium and potassium silicates for industrial use Part 11: Determination of chloride content of sodium metasilicate NOTEIt is recommended that this Part be read in conjunction with the information in the “General introduction” publis
2、hed separately as BS 6092-0. UDC 661.683/.684:546.32284 + 546.33284:543.24.062:546.131 Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:10:23 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6092-11:1981 This British Standard, having been prepared under the direction of the Chemicals Standards
3、 Committee, was published under the authority of the Executive Board and comes into effect on 27 February 1981 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference CIC/22 Draft for comment 73/55424 DC ISBN 0 580 12048 1 A British Standard does not purport
4、 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 immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cove
5、r, pages 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 issueCom
6、ments Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:10:23 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6092-11:1981 BSI 12-1999i Contents Page 1Scope1 2References1 3Principle1 4Reagents1 5Apparatus1 6Procedure1 7Expression of results1 Publications referred toInside back cover Licensed C
7、opy: sheffieldun sheffieldun, na, Wed Dec 06 14:10:23 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:10:23 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6092-11:1981 BSI 12-19991 1 Scope This Part of BS 6092 describes a method of test fo
8、r determining the chloride content of sodium metasilicate pentahydrate and is applicable to products having chloride contents, expressed as sodium chloride (NaCl) in the range 0.03 % to 0.55 % (m/m). There is no International Standard corresponding to this Part of BS 6092. 2 References The titles of
9、 the publications referred to in this standard are listed on the inside back cover. 3 Principle A solution of the test portion is mixed with silver nitrate solution and the excess of silver nitrate is titrated with ammonium thiocyanate solution using ammonium iron (III) sulphate solution as indicato
10、r. 4 Reagents The following reagents are required and shall be of recognized analytical quality. Water complying with the requirements of BS 3978 shall be used throughout. 4.1 Nitrobenzene. WARNING. Serious risk of poisoning by inhalation, swallowing or skin contact. Avoid breathing vapour. Prevent
11、contact with skin and eyes. 4.2 Nitric acid, approximately 5 N solution. 4.3 Silver nitrate, 0.1 N standard volumetric solution. 4.4 Ammonium thiocyanate, 0.1 N standard volumetric solution. 4.5 Ammonium iron (III) sulphate indicator solution, 100 g/l. Dissolve 25 g of ammonium iron (III) sulphate i
12、n 250 ml of water. Allow the solution to settle and decant if necessary. If the solution is still not clear, add a few drops of approximately 5 N nitric acid solution. 5 Apparatus Ordinary laboratory apparatus is required. 6 Procedure 6.1 Test portion. Weigh, to the nearest 0.1 g, 10 g of the sample
13、. 6.2 Determination. Transfer the test portion (6.1) to a 500 ml stoppered flask (an iodine flask, complying with the requirements of BS 2735 is suitable). Add 250 ml of water, warming if necessary to complete dissolution of the solid. Cool the solution to room temperature and add 25 ml of the nitri
14、c acid solution (4.2). Prepare a blank solution from 250 ml of water and 25 ml of the nitric acid solution (4.2) in a second, similar, flask. To each flask add 10 ml of the silver nitrate solution (4.3) from a pipette, followed by 2 ml of the nitrobenzene (4.1) and 1 ml of the ammonium iron (III) su
15、lphate indicator solution (4.5). Stopper the flasks and shake them for about 30 s. Titrate the blank solution with the ammonium thiocyanate solution (4.4) until a faint pink-brown colour just persists throughout the solution. Similarly titrate the test solution to a matching end-point. 7 Expression
16、of results The chloride content, expressed as a percentage by mass of sodium chloride (NaCl), is given by the formula: where V1is the volume of the ammonium thiocyanate solution (4.4) required for the blank test, in ml; V2is the volume of the ammonium thiocyanate solution (4.4) required for the test
17、 solution, in ml; 10 is the mass of the test portion, in g. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:10:23 GMT+00:00 2006, Uncontrolled Copy, (c) BSI 2 blank Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:10:23 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6092-11:1981 BS
18、I 12-1999 Publications referred to BS 2735, Iodine flasks. BS 3978, Water for laboratory use. Licensed Copy: sheffieldun sheffieldun, na, Wed Dec 06 14:10:23 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 6092-11: 1981 BSI 389 Chiswick High Road London W4 4AL BSI British Standards Institution BSI is
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