ISO 4281:1977

Sodium hexafluorosilicate for industrial use - Determination of free acidity and total hexafluorosilicate content - Titrimetric method

With respect to the free acidity, applicable to products having contents, expressed as H2 SiF6 , equal to or more than 0,1 % (m/m). First, determination of the free acid contents by titration of an ice-cooled test portion with a standard volumetric sodium hydroxide solution in the presence of potassium nitrate and using bromothymol blue as indicator, then, followed by titration at near boiling temperature with standard volumetric sodium hydroxide solution to the appearance of a permanent blue colour.

Hexafluorosilicate de sodium à usage industriel — Détermination de l'acidité libre et de la teneur en hexafluorosilicate total — Méthode titrimétrique

General Information

• Status: Published
• Publication Date: 28-Feb-1977
• ICS: 71.060.50 - Salts
• Technical Committee: ISO/TC 47 - Chemistry
• Drafting Committee: ISO/TC 47 - Chemistry
• Current Stage: 9093 - International Standard confirmed
• Start Date: 29-Nov-2023
• Completion Date: 13-Dec-2025

Overview

ISO 4281:1977 specifies a titrimetric method for the determination of free acidity and total hexafluorosilicate content in sodium hexafluorosilicate intended for industrial use. It applies to products with a free acidity, expressed as hexafluorosilicic acid (H2SiF6), of 0.1% (m/m) or higher. The standard details procedures for:

• Measuring free acidity through cold titration using sodium hydroxide
• Determining total hexafluorosilicate content by titration at near boiling temperature

This method offers reliable and reproducible chemical analysis crucial for quality control and compliance in industrial processes involving sodium hexafluorosilicate.

Key Topics

• Scope and Applicability
  Applicable to sodium hexafluorosilicate with a minimum free acidity of 0.1% (m/m) expressed as H2SiF6.

• Titrimetric Principle

  • Cold titration: Measures free acidity using a standard volumetric sodium hydroxide (NaOH) solution at low temperature with bromothymol blue as an indicator in the presence of potassium nitrate.
  • Hot titration: Measures total hexafluorosilicate content by titrating near boiling temperature until a persistent blue color appears.

• Reagents and Apparatus
  Utilizes analytical-grade reagents such as sodium hydroxide solutions (0.1 N and 0.5 N), potassium nitrate saturated solution, bromothymol blue indicator, and distilled water. Standard laboratory equipment is required including glass weighing bottles, beakers, and a hot-plate.

• Safety Considerations
  Sodium hexafluorosilicate is poisonous and poses risks on inhalation and contact. The standard emphasizes precautions such as wearing respirators and goggles and thorough washing after handling.

• Calculation of Results
  Formulas are provided to calculate:

  • Free acidity expressed as hydrochloric acid (HCl) or hexafluorosilicic acid (H2SiF6)
  • Total hexafluorosilicate content expressed as sodium hexafluorosilicate (Na2SiF6)

• Reporting
  Test reports should include method references, results, expression methods, and note any unusual observations or deviations from the standard procedure.

Applications

ISO 4281:1977 is essential in industries using sodium hexafluorosilicate, including:

• Chemical Manufacturing
  Ensures purity and appropriate acidity levels for sodium hexafluorosilicate used in further chemical syntheses.

• Water Treatment
  Quality control of sodium hexafluorosilicate used for fluoridation and water purification.

• Glass and Ceramics Production
  Monitoring raw material specifications for hexafluorosilicate content critical to batch formulations.

• Environmental and Health Safety Compliance
  Accurate determination of acidity and fluorosilicate content helps manage safety risks related to handling and processing the compound.

• Research and Development
  Analytical baseline for testing new batches or formulations of sodium hexafluorosilicate in laboratory settings.

Related Standards

For comprehensive quality control and chemical characterization of sodium hexafluorosilicate, consider these related ISO standards:

• ISO 5440 – Determination of phosphate content
• ISO 5441 – Determination of calcium content (EDTA titrimetric method)
• ISO 5442 – Determination of sulfur compounds content (iodometric method)
• ISO 5443 – Determination of iron content (1,10-Phenanthroline spectrophotometric method)
• ISO 5444 – Determination of loss in mass at 105 °C

These complementary standards support a full profile analysis ensuring product consistency, safety, and regulatory adherence in industrial applications involving sodium hexafluorosilicate.

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Keywords: ISO 4281, sodium hexafluorosilicate, free acidity determination, hexafluorosilicate content, titrimetric method, chemical analysis, industrial standards, sodium hydroxide titration, bromothymol blue indicator, quality control, industrial chemical testing.

Standards Content (Sample)

INTERNATIONAL STANDARD
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION #MEXLZYHAPOAHAfl OPTAHM3AUMfl I-Io ~AHLIAPT213AWW~ORGANISATION INTERNATIONALE DE NORMALISATION
Sodium hexafluorosilicate for industrial use - Determination
of free acidity and total hexafluorosilicate content -
Titrimetric method
Determinations de l’acidite libre et de Ia teneur
Hexafluorosilicate de sodium 2 usage industriel -
en hexa fluorosilica te total - AMhode titrimktrique
First edition - 1977-03-01
Ref. No. ISO 4281-1977 (E)
UDC 661.833 : 543.241.5
Chemical analysis, determination of content, acidity, sodium fluorsilicate, volu-
Descriptors : Chemical compounds, sodium fluorsilicate,
metric analysis.
Price based on 2 pages
ISO (the International Organization for Standardization) is a worldwide federation
of national Standards institutes (ISO member bodies). The work of developing
International 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 right to be represented on that committee. International organizations,
governmental 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 approval before their acceptance as International
Standards by the ISO Council.
International Standard ISO 4281 was developed by Technical Committee
ISO/TC 47, Chemistry, and was circulated to the member bodies in August 1975.
lt has been approved by the member bodies of the following countries :
Belgium India Spain
Brazil Israel Switzerland
Czechoslovakia I taly Turkey
Egypt, Arab Rep. of Mexico United Kingdom
France Poland U.S.S. R.
Germany Romania
Hungary South Africa, Rep. of
No member body expressed disapproval of the document.
0 International Organkation for Standardkation, 1977 l
Printed in Switzerland
ISO 4281-1977 (E)
INTERNATIONAL STANDARD
Sodium hexafluorosilicate for industrial use - Determination
of free acidity and total hexafluorosilicate content -
Titrimetric method
WARNING - Sodium hexafluorosilicate is poisonous if taken internally. Breathing of the dust should be avoided. Contact
with the eyes and skin should be prevented and Operators should wash thoroughly after handling the material and should
wear a respirator and goggles when handling the powdered material.
4 REACTIONS
1 SCOPE AND FIELD OF APPLICATION
Cold titration
This International Standard specifies a titrimetric method
for the determination of the free acidity and the total
-+ Na,SiFe + 2H,O
H,SiFe + 2NaOH
hexafluorosilicate content of sodium hexafluorosilicate
for industrial use. In respect of free acidity, it is applicable
Hot titration
to products having free acidities, expressed as a percentage
by mass of hexafluorosilicic acid (H$iFe), equal to or
Na,SiFe + 4NaOH -+ 6NaF + SiO, + 2H,O
greater than 0,l.
5 APPARATUS
2 PRINCIPLE
Ordinary laboratory apparatus.
Determination of the free acidity by titration of an ice-cold
test Portion with a Standard volumetric sodium hydroxide
6 PROCEDURE
Solution in the presence of potassium nitrate and using
bromothymol blue as indicator, followed by titration at
6.1 Test Portion
near boiling temperature to determine the total hexafluoro-
In a glass weighing bottle, weigh, to the nearest 0,001 g,
silicate content.
between 1,00 and 1,20 g of the test Sample.
6.2 Determinations
3 REAGENTS
Transfer the test Portion (6.1) quantitatively to a 500 ml
During the analysis, use only reagents of analytical grade
beaker containing about 100 g of the crushed ice (3.1)
and only distilled water or water of equivalent purity.
and 25 ml of the potassium nitrate Sol
...

NORME INTERNATIONALE
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION .ME’WCAYHAPOAHAA OPI-AHW3ALUM n0 CTAHJIAPTM3Al.W4~ORGANISATION INTERNATIONALE DE NORMALISATION
Hexafluorosilicate de sodium à usage industriel -
Déterminations de l’acidité libre et de la teneur en
hexafluorosilicate total - Méthode titrimétrique
Determination of free acidity and total
Sodium hexafluorosilicate for industrial use -
hexa fluorosilica te content - Titrime trie method
Première édition - 1977-03-01
Réf. no : ISO 4281-1977 (F)
CDU 661.833 : 543.241.5
analyse chimique, dosage, acidité, fluorsilicate de sodium, méthode volumétrique.
Descripteurs : composé chimique, fluorsilicate de sodium,
Prix basé sur 2 pages
AVANT-PROPOS
L’ISO (Organisation internationale de normalisation) est une fédération mondiale
d’organismes nationaux de normalisation (comités membres de I’ISO). L’élaboration
des Normes internationales est confiée aux comités techniques de I’ISO. Chaque
comité membre intéressé par une étude a le droit de faire partie du comité technique
correspondant. Les organisations internationales, gouvernementales et non
gouvernementales, en liaison avec I’ISO, participent également aux travaux.
Les projets de Normes internationales adoptés par les comités techniques sont
soumis aux comités membres pour approbation, avant leur acceptation comme
Normes internationales par le Conseil de I’ISO.
La Norme internationale ISO 4281 a été élaborée par le comité technique
ISO/TC 47, Chimie, et a été soumise aux comités membres en août 1975.
Les comités membres des pays suivants l’ont approuvée :
Afrique du Sud, Rép. d’ Royaume-Uni
Hongrie
Allemagne Inde Suisse
Belgique Israël Tchécoslovaquie
Brésil Italie Turquie
Égypte, Rép. arabe d’ Mexique U.R.S.S.
Espagne Pologne
France Roumanie
Aucun comité membre ne l’a désapprouvée.
@ Organisation internationale de normalisation, 1977 l
Imprimé en Suisse
NORME INTERNATIONALE ISO4281-1977( F)
Hexafluorosilicate de sodium à usage industriel -
Déterminations de l’acidité libre et de la teneur en
hexafluorosilicate total - Méthode titrimétrique
AVERTISSEMENT - L’hexafluorosilicate de sodium est toxique s’il est absorbé. II faut éviter d’en respirer la poussière.
Empêcher tout contact avec les yeux et la peau. Les opérateurs devront se laver soigneusement après manipulation du produit,
et devront porter un appareil respiratoire et des lunettes protectrices lorsqu’ils manipuleront le produit réduit en poudre.
1 OBJET ET DOMAINE D’APPLICATION 4 RÉACTIONS
La présente Norme internationale spécifie une méthode Titrage à froid
titrimétrique pour les déterminations de l’acidité libre et de
H,SiF, + 2NaOH -+ Na,SiF, + 2H,O
la teneur en hexafluorosilicate total de I’hexafluorosilicate
de sodium à usage industriel. Pour ce qui concerne l’acidité
Titrage à chaud
libre, la méthode est applicable aux produits ayant une
acidité libre, exprimée en pourcentage en masse d’acide
Na*SiF, + 4NaOH + 6NaF + SiO, + 2H,O
hexafluorosilicique (H$iFe), égale ou supérieure à 0,l.
2 PRINCIPE 5 APPAREILLAGE
Détermination de l’acidité libre par titrage d’une prise Matériel courant de laboratoire.
d’essai refroidie dans la glace, avec une solution titrée
d’hydroxyde de sodium, en présence de nitrate de potas-
sium et en utilisant du bleu de bromothymol comme indi-
cateur. Poursuite du titrage à une température proche du
6 MODE OPÉRATOIRE
point d’ébullition pour déterminer la teneur totale en hexa-
fluorosil icate.
6.1 Prise d’essai
Dans un vase à peser en verre, peser, à 0,001 g près, entre
3 RÉACTIFS
1,OO et 1,20 g de l’échantillon pour essai.
Au cours de l’analyse, n’utiliser que des réactifs de qualité
analytique reconnue, et que de l’eau distillée ou de l’eau
6.2 Déterminations
de pureté équivalente.
Transférer quantitativement la prise d’essai (6.1) dans un
3.1 Glace pilée, préparée à partir d’eau distillée ou d’eau bécher de 500 ml contenant 100 g environ de la glace
...