1、Inorganic chemical products for industrial use - method for determination of chloride content - Mercurimetric method General Produits chimiques inorganiques usage industriel - Mthode gnrale de dosage des chlorures - M fhode rnercurimtrique First edition - 1979-07-15 Copyright International Organizat
2、ion for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-._ - - 5770-79 Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards institutes (IS0 member bod
3、ies). The work of developing Interna- tional 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 represented on that committee. International organizations, governmental and non- gove
4、rnmental, 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 Standards by the IS0 Council. International Standard IS0 5790 was developed by Techni
5、cal Committee ISO/TC 47, Chemistry, and was circulated to the member bodies in June 1977. It has been approved by the member bodies of the following countries : Austria Belgium Brazil Bulgaria Chile Czechoslovakia Egypt, Arab Rep. of France Germany, F.R. Hungary India Israel Italy Kenya Korea, Rep.
6、of New Zealand No member body expressed disapproval of the document. Poland Romania South Africa, Rep. of Switzerland Turkey United Kingdom USSR Y ugoslavia O In srnational Organization fo Printed in Switzerland Standardization, 1979 0 Copyright International Organization for Standardization Provide
7、d by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Inorganic chemical products for industrial use - General method for determination of chloride content - Mercurimetric method 1 Scope This International Standard specifies a general mercu
8、rimetric method for the determination of chloride content. 2 Field of application The method is applicable to inorganic chemical products for industrial use. It enables quantities of chloride (Ci-) exceeding 1 mg in the test portion to be determined with an absolute error of 0,2 to 0,5 mg, according
9、 to the concentration of the stan- dard volumetric solution used. The determination is not affected by the elements or com- pounds listed in annex A when they are present in quantities up to the specified limits. In certain cases, this annex contains instructions for the treat- ment to be applied to
10、 reduce or eliminate interferences. 3 Principle Conversion of CI- ions into weakly ionized mercuryll) chloride, using highly ionized standard volumehric mercuryll) nitrate solution. Detection of the end-point by reaction of the excess of mercury(ll) nitrate with 1,5-diphenylcarbazone used as an indi
11、cator, by the appearance of a violet colour. 4 Reagents During the analysis, use only reagents of recognized analytical grade and only distilled water or water of equivalent purity. 4.1 Nitric acid, e I 1,4 g/ml, approximately 68 % (rn/rn) solution, of which the chloride content, expressed as chlori
12、ne (CI), is not greater than 0,5 mg/kg. 4.2 Nitric acid, approximately 126 g/l solution, prepared by dilution of the nitric acid solution (4.1). 4.3 Sodium hydroxide, approximately 80 g/l solution of which the chloride content, expressed as chlorine (CI) is not greater than 5 mg/kg. 4.4 Sodium chlor
13、ide, standard reference solution, c (NaCl) = 0,l mol/l1. Weigh, to the nearest 0,OOO 1 g, 5,844 2 g of sodium chloride, previously dried for 1 h at approximately 500 OC and cooled in a desiccator, and dissolve in water. Transfer the solution quan- titatively to a 1 O00 ml one-mark volumetric flask,
14、dilute to the mark and mix. 4.5 Sodium chloride, standard reference solution, c(NaCI1 = 0.05 moi/P). Place 100,O ml of the standard reference solution (4.4) in a 200 mi one-mark volumetric flask, dilute to the mark and mix. 4.6 Sodium chloride, standard reference solution, ciNaCl) = 0,02 mol/B). Pla
15、ce 100,O ml of the standard reference solution (4.4) in a 500 ml one-mark volumetric flask, dilute to the mark and mix. 4.7 Standard end-point matching solution. Prepare this solution at the time of use. Do not use the solution for more than 30 min after preparation. Place the same volume of water a
16、s in the test solution (6.2.1) in a 500 ml conical flask, add 3 drops of the bromophenol blue solution (4.11) and the nitric acid solution (4.21, drop by drop, until the colour changes from blue to yellow. Add an excess of 3 drops of this acid, 0,5 to 1,0 ml of the diphenylcarbazone solution (4.12)
17、and, from the burette bl, the minimum volume of the standard volumetric mercury(l1) nitrate solution (4.8,4.9 or 4.10) necessary to change the colour of the solution from yellow to mauve. 1) Previously 0,l N 2) Previously 0,05 N 3) Previously 0,02 N I Copyright International Organization for Standar
18、dization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-IS0 RW-1979 (E) 4.8 Mercury(ll1 nitrate, standard volumetric solution, dl /2 Hg(N031,. H,Ol = O, 1 moI/W, Use this solution to determine quantities greater than 20 mg of
19、chloride (CI-) in the test portion. 4.8.1 Preparation of the solution Weigh 10,85 IT 0,Ol g of mercuryill) oxide (HgO) and dissolve in 10 ml of the nitric acid solution (4.11, Transfer the solution quantitatively to a 1 O00 ml one-mark volumetric flask, dilute to the mark and mix. NOTE - This soluti
20、on may also be prepared by dissolution of a mass of 17,13 g of mercuryll) nitrate monohydrate HgNO,),. H,Ol in water acidified with 1 ml of the nitric acid solution (4.1). Standardize this solution following the procedure specified in 4.8.2 and adjust it, if necessary, to exactly Oll mol/l. 4.8.2 St
21、andardization of the solution Place 40,O ml of the standard reference sodium chloride solution (4.41,160 ml of water and 3 drops of the bromophenol blue solution (4.11) in a 500 ml conical flask. Add the nitric acid solution (4.21, drop by drop, until the colour of the indicator changes from blue to
22、 yellow and then add an excess of 3 drops of this acid and the volume of the diphenylcarbazone solution (4.12) added for the standard end-point matching solution (4.7). Titrate (see note in 6.2.2) with the mercury(l1) nitrate solution (4.8.1 1 to be standardized until the colour matches the mauve of
23、 the standard end-point matching solution and deduct the volume of the mercury(ll1 nitrate solution (4.8.1) added during the preparation of this standard end-point matching solution (generally 1 drop). The volume corresponding to exactly Oll mol/l is 40,O ml. NOTE - Store the residual solution obtai
24、ned from the titration and treat it as specified in annex B, so as to avoid the pollution of waste water by the mercury. 4.9 Mercury(l1) nitrate, standard volumetric solution, d1/2 Hg(N03),H201 = 0,05 mo1/12)- Use this solution to determine quantities between 1 and 20 mg of chloride (CI-) in the tes
25、t portion. 4.9.1 Preparation of the solution Use one of the two following methods : - dilute 100 ml of the solution (4.8.1) to the mark in a 200 ml one-mark volumetric flask and mix, or - weigh 5,43 f 0,Ol g of mercuryill) oxide (HgO) and dissolve in 10 ml of the nitric acid solution (4.1). Transfer
26、 the solution quantitatively to a 1 O00 ml one-mark volumetric flask, dilute to the mark and mix, See note in 1) Previously 0,l N 21 Previously 0,05 N 3) Previously 0,02 N 2 4.8.1 for the use of 8,565 g of mercuryll) nitrate monohydrate.1 Standardize this solution following the procedure specified i
27、n 4.9.2 and adjust it, if necessary, to exactly 0,05 mol/l. 4.9.2 Standardization of the solution Place 10,O ml of the standard reference sodium chloride solution (4.51, 190 ml of water and 3 drops of the bromophenol blue solution (4.1 1) in a 500 ml conical flask. Add the nitric acid solution (4.21
28、, drop by drop, until the colour of the indicator changes from blue to yellow and then add an excess of 3 drops of this acid and the volume.of the diphenylcarbazone solution (4.12) added for the standard end-point matching solution (4.7). Titrate (see note in 6.2.2) with the mercuryll) nitrate solut
29、ion (4.9.1) to be standardized until the colour matches the mauve of the standard end-point matching solution and deduct the volume of the mercuryll) nitrate solution (4.9.1) added during the preparation of this standard end-point matching solution (generally 2 drops). The volume corresponding to ex
30、actly 0,05 mol/l is 10,OO ml. 4.10 Mercury(l1) nitrate, standard volumetric solution, c(1/2 Hg(N03),.H,01 = 0,02 mo1/13). Analysts who can easily detect the diphenylcarbazone colour change can take advantage of this solution to determine quantities between 1 and 5 mg of chloride (CI-) in the test po
31、rtion. 4.10.1 Preparation of the solution Use one of the two following methods : - dilute 100 ml of the solution (4.8.1) to the mark in a 500 ml one-mark volumetric flask and mix, or - weigh 2,18 IT 0,OI g of mercury(l1) oxide (HgO) and dissolve in 10 ml of the nitric acid solution (4.1). Transfer t
32、he solution quantitatively to a 1 o00 ml one-mark volumetric flask, dilute to the mark and mix. See note in 4.8.1 for the use of 3,43 g of mercury(l1) nitrate monohydrate. Standardize this solution following the procedure specified in 4.10.2 and adjust it, if necessary, to exactly 0,02 mol/l. 4.10.2
33、 Standardization of the solution Place 5,00 ml of the standard reference sodium chloride solution (4.61, 195 ml of water and 3 drops of the bromophenol blue solution (4.1 1) in a 500 ml conical flask. Add the nitric acid solution (4.21, drop by drop, until the colour changes from blue to yellow and
34、then add an excess of 3 drops of this acid and the volume of the diphenylcarbazone solution (4.12) added for the standard end-point matching solutuon (4.71. Titrate (see note in 6,2.2) with the mercuryll) nitrate solution to be standardized _ _- 5790-79 -1 4851903 0042845 E I Copyright International
35、 Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-5770-77 (4.10.1) until the colour matches the mauve of the standard ent-point matching solution and deduct the volume of the mer- cury(l1) nitrat
36、e solution (4.10.1 1 added during the preparation of this standard end-point matching solution. The volume corresponding to exactly 0,02 mol/l is 5,OO ml. 4.11 Bromophenol blue, 1 g/l solution in 95 % (V/M ethanol. 4.12 1,5Diphenylcarbazone, 5 g/l solution in 95 % (V/M ethanol. Store this solution i
37、n a refrigerator and replace it when it no longer gives a sharp colour change. 5 Apparatus Ordinary laboratory apparatus, and 5.1 Burette, of capacity 50 ml, complying with the requirements of class A of ISO/R 385, having a fine point enabling 30 drops per millilitre to be delivered. 6 Procedure 6.1
38、 Test portion Weigh a quantity of the test sample not exceeding 10 g, con- taining between 1 and 175 mg of chloride (CI-) and not con- taining more than one of the intererences listed in annex A, clause A.l, or all of the interferences listed in annex A, clause A.2. 6.2 Determination 6.2.1 Preparati
39、on of the test solution Transfer the test portion (6.1) to a 500 ml conical flask and, according to the solubility of the sample, add between 50 and 350 ml of water. Neutralize it with care using the nitric acid solution (4.1) or the sodium hydroxide solution (4.3). Dilute, if necessary, to obtain i
40、n the conical flask a volume between 200 and 350 ml, cool to room temperature, add 3 drops of the bromophenol blue solution (4.1 1) and then add successively : - colour changes to yellow; - the colour changes to blue; the nitric acid solution (4.21, if necessary, until the the sodium hydroxide solut
41、ion (4.31, drop by drop, until - the nitric acid solution (4.2) until the colour changes to yellow; - an excess of 3 drops of this acid (4.2). 6.2.2 Titration of the test solution Add to the test solution (6.2.1) the volume of the diphenylcarbazone solution (4.12) added for the standard end- point m
42、atching solution (4.7) and titrate with the appropriate standard volumetric mercury(l1) nitrate solution (4.8, 4.9 or 4.10) until the colour matches the mauve of the standard end-point matching solution. NOTE - Stir genty during the titration so as to avoid the formation of foam which may absorb the
43、 indicator and thereby obscure the colour change. Add the standard volumetric solution slowly and reduce the speed of flow sharply towards the end of the titration so as to enable the last traces of chloride to react with the mercuryll) nitrate solution. Store the residual solutions obtained from th
44、e titration and treat them as specified in annex B, so as to avoid the pollution of waste water by the mercury. 7 Expression of results The chloride content, expressed as a percentage by mass of chloride (CI), is given by the formula 100 (V, - V,) x c x 0,035453 x - rn where V, is the volume, in mil
45、lilitres, of the standard volumetric mercury(l1) nitrate solution (4.8, 4.9 or 4.10) used for the determination; Vl is the volume, in millilitres, of the standard volumetric mercuryll) nitrate solution (4.8, 4.9 or 4.10) used for the preparation of the standard end-point matching solution (4.7); c i
46、s the concentration, expressed in moles per litre, of the standard volumetric rnercury(l1) nitrate solution used (see 4.8.2, 4.9.2 or 4.10.2); m is the mass, in grams, of the test portion (6.1); 0,035 453 is the mass, in grams, of chlorine corre- sponding to 1 ml of mercury(l1) nitrate solution c1/2
47、 Hg(NO,),.H,01 = 1 mol/ll) exactly. 1) Previously 1 N 3 Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-8 Test report The test report shall include the following particul
48、ars : a) an identification of the sample; b) the reference of the method used; _ i - 5790-79 3 4853903 0042847 b I c) the results and the method of expression used; d) any unusual features noted during the determination; e) any operation not included in this International Standard, or regarded as op
49、tional. Copyright International Organization for Standardization Provided by IHS under license with ISONot for ResaleNo reproduction or networking permitted without license from IHS-,-,-5790-79 4853903 0042848 is0 R90-1979 (E) I Annex A Table of interferences A.l Interferences present separately Reason for the limit and possible remedy Limit of non-interference loo gll Element or compound NaNO, KNO, 100 gll NO3 70 gll Slight buffer eff
