5196/1 (ISO International Standard INTERNATIONAL ORGANIZATION FOR STANDARDIZATION+MEXAYHAPOAHAR OPFAHM3AUWA NO CTAHAAPTM3AUWW-ORGANISATION INTE RNATIONALE DE NORMALISATION Magnesium alloys -- Determination of thorium Part 1 : Gravimetric method Alliages de magnésium - Dosage du thorium - Partie 1 : Méthode gravimetrique First edition - 1980-11-15 ISO 5196/1-1980 (E) UDC 669.721 : 543.21 : 546.841 Ref. No. 1SO 5196/1-1980 (E) Descriptors : magnesium alloys, chemical analysis, determination of content, thorium, titration, gravimetric analysis. Price based on 2 pages Copyright International Organization for Standardization Not for Resale Foreword Iso (the International Organization for Standardization) is a worldwide federation of national standards institutes (IsO member bodies). The work of developing Inter national Standards is carried out through IsO technical committees. Every member body interested in a subject for which a technical committee has been set up has the and non-governmental, 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 approvai before their acceptance as international Standards by the ISO Council. Standard ISo 5196/1 was developed by Technical Committee International ISO/Tc 79, Light metals and their alloys, and was circulated to the member bodies in August 1979. India South Africa, Rep. of Australia Italy Spain Austria Japan Sweden China Norway United Kingdom Czechoslovakia Philippines USSR France Germany, F. R. Portugal Yugoslavia Hungary Romania No member body expressed disapproval of the document. International Organization for Standardization, 1980 Printed in Switzerland Copyright International Organization for Standardization fromIHS ISO 5196/1-1980 (E) INTERNATIONAL STANDARD Magnesium alloys -- Determination of thorium Part 1 : Gravimetric method 3.6 Benzoic acid, 20 g/l solution. 1 Scope and field of application This International Standard specifies a gravimetric method for Dissolve 20 g of benzoic acid (CsHsCOOH) in hot water. Allow the determination of thorium in magnesium alloys. to cool, filter if necessary, make up the volume to 1 000 ml and mix. The method is applicable to products having thorium contents between 0,2 and 5,0 % (m/m). 3.7 Benzoic acid, 2,5 g/l solution. Dissolve 2,5 g of benzoic acid (CsHsCOOH) in hot water, make 2 Principle up the volume to 1 000 ml and mix. Dissolution of a test portion in hydrochloric acid. 3.8 Oxalic acid, saturated solution at ambient temperature. Preliminary separation of the thorium in the form of its ben- Dissolve 150 g of oxalic acid [(C00H)2.2H20] in 1 000 ml of hot zoate. water. Allow to cool and filter. Dissolution of the precipitate and reprecipitation of the thorium in the form of its oxalate. Caicination and weighing of the 3.9 Oxalic acid washing solution. thorium oxide. Dilute 70 ml of the oxalic acid solution (3.8) to 500 ml with water. 3 Reagents 3.10 Bromophenol blue, 4 g/l alkaline solution. During the analysis, use only reagents of recognized analytical quality and only distilled water or water of equivalent purity. Piace 0,4 g of bromophenol blue in a mortar, add 8,25 ml of 5 g/l sodium hydroxide solution and crush until completely 3.1 Hydroxylammonium chloride (NH2OH.HCI). dissolved. Transfer quantitatively into a 100 ml one-mark volumetric flask, make up to the mark with water and mix. 3.2 Ammonium chloride (NH4CI). 3.3 Hydrochloric acid (o approximately 1,19 g/ml), 38 % 4. Apparatus (m/ m) or approximately 12 mol/l solution. Ordinary laboratory apparatus. 3.4 Hydrochloric acid (o approximately 1,05 g/ml) or ap- proximately 3 mol/l solution. Dilute 250 ml of the hydrochloric acid solution (3.3) with water, 5 Sampling make up the volume to 1 000 ml and mix. 5.1 Laboratory sample1) 3.5 Ammonium hydroxide solution (o approximately 0,97 g/ml). 5.2 Test sample Dilute 250 ml of ammonium hydroxide solution (o approxi Chips having a