BS-5688-5-1979 ISO-1918-1972.pdf
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1、BRITISH STANDARD BS 5688-5: 1979 ISO 1918:1972 Methods of Test for boric acid, boric oxide, disodium tetraborates, sodium perborates and crude sodium borates for industrial use Part 5: Determination of sulphur compounds in boric acid, boric oxide, disodium tetraborates and crude sodium borates ISO t
2、itle: Boric acid, boric oxide, disodium tetraborates and crude sodium borates for industrial use Determination of sulphur compounds 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
3、 661.65:546.273:543.062:546.22 Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:50:41 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5688-5:1979 This British Standard, having been prepared under the direction of the Chemicals Standards Committee, was published under the authority of the Exec
4、utive Board on 28 February 1979 BSI 12-1999 The following BSI references relate to the work on this standard: Committee reference CIC/16 Draft for comment 74/53496 DC ISBN 0 580 10538 5 National foreword This Part of BS 5688 is identical with ISO 1918 “Boric acid, boric oxide, disodium tetraborates
5、and crude sodium borates, for industrial use Determination of sulphur compounds Volumetric method” published by the International Organization for Standardization (ISO). Terminology and conventions. The text of the International Standard has been approved as suitable for publication, without deviati
6、on, as a British Standard. Some terminology and certain conventions are not identical with those used in British Standards; attention is drawn to the following. The comma has been used throughout as a decimal marker. In British Standards it is current practice to use a full point on the baseline as
7、the decimal marker. Where the words “International Standard” appear, referring to this standard, they should be interpreted as “British Standard”. Additional information Water. Water complying with the requirements of clause 3 is specified in BS 3978 “Water for laboratory use”. Reagents. Unless othe
8、rwise stated, it is essential that the reagents used in this determination be of recognized analytical grade. Hydrochloric acid, approximately 1.18 g/ml, about 36 % (m/m) solution, which is the corresponding reagent normally obtainable in the United Kingdom, is suitable for use in place of the solut
9、ion specified in 3.3. 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 immunity from legal obligations. Summary of pages Th
10、is document comprises a front cover, an inside front cover, 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. Cro
11、ss-reference International StandardCorresponding British Standard ISO/R 383 (now ISO 383)BS 572:1960 Interchangeable conical ground glass joints (Related) Amendments issued since publication Amd. No.Date of issueComments Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:50:41 GMT+00:00 2006,
12、 Uncontrolled Copy, (c) BSI BS 5688-5:1979 BSI 12-1999i Contents Page National forewordInside front cover 1Scope and field of application1 2Principle1 3Reagents1 4Apparatus1 5Procedure1 6Expression of results2 7Test report2 Figure Apparatus (4.1)2 Publication referred toInside back cover Licensed Co
13、py: sheffieldun sheffieldun, na, Mon Dec 04 15:50:41 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ii blank Licensed Copy: sheffieldun sheffieldun, na, Mon Dec 04 15:50:41 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS 5688-5:1979 BSI 12-19991 1 Scope and field of application This International Standard
14、 specifies a volumetric method for the determination of sulphur compounds in boric acid, boric oxide, disodium tetraborates and crude sodium borates for industrial use. 2 Principle Reduction of sulphur compounds to hydrogen sulphide by heating with a mixture of hydriodic acid and hypophosphorous aci
15、d. Absorption of the evolved hydrogen sulphide in a mixture of sodium hydroxide and acetone, followed by titration with mercuric acetate standard volumetric solution using dithizone as indicator. 3 Reagents Distilled water or water of equivalent purity shall be used in the test. 3.1 Acetone 3.2 Nitr
16、ogen, oxygen free. 3.3 Hydrochloric acid, 1,19 g/ml approximately 38 % (m/m) solution. 3.4 Sodium hydroxide, approximately N solution. 3.5 Reducing solution In a 500 ml round-bottomed flask, fitted with a ground glass joint, mix 50 ml of hypophosphorous acid, 50 % (m/m), 100 ml of the hydrochloric a
17、cid solution (3.3), 120 ml of hydriodic acid, 1,9 g/ml approximately. Attach a reflux condenser and insert a glass tube down the condenser to permit the introduction of a stream of nitrogen (3.2) into the mixture. Boil under reflux for 4 h, allowing a continuous stream of nitrogen to pass through th
18、e mixture. Allow the mixture to cool while the nitrogen is still flowing. Store in a dark coloured glass bottle. 3.6 Mercury(II) acetate, 0,001 M standard volumetric solution. Dissolve 0,318 7 g of mercury (II) acetate in water and dilute to 1 000 ml. 3.7 Dithizone, 1 g/l solution in acetone. Dissol
19、ve 0,1 g of dithizone in 100 ml of acetone (3.1). 4 Apparatus Ordinary laboratory apparatus and 4.1 Apparatus as illustrated in the Figure, fitted with ground glass joints1) and comprising the following components: A) Flask, round-bottomed, with one central neck and one angled side neck; B) Condense
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