ISO 3423:1975 PDF

Sulphuric acid and oleums for industrial use — Determination of sulphur dioxide content — Iodometric method

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Title (English):

ISO 3423:1975

Sulphuric acid and oleums for industrial use — Determination of sulphur dioxide content — Iodometric method

Document status:: Active
Format:: Electronic (PDF)
Number of pages:: 3
Publication date:: November 1, 1975
Edition:: ISO IS 3423 edition 1 version 1
ICS:: 71.060.30

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Description (English):

Applicable of products the SO2 content of which is equal to or more than 2 mg/kg. Based on the displacement of the sulphur dioxide present in the test portion by a current of pure nitrogen and absorption in a known volume of iodine solution. Titration of the excess of iodine with standard volumetric sodium thiosulphate solution. The diagram of the glass apparatus for absorption is shown in a figure.

Technical details

Technical committee: ISO/TC 47 - Chemistry
SKU: ISO 3423:1975

Abstract

Overview

ISO 3423:1975 specifies an iodometric method for determining sulphur dioxide (SO2) content in sulphuric acid and oleums for industrial use. The procedure is applicable to products with SO2 content of 2 mg/kg or more and is intended for routine laboratory analysis and industrial quality control. The method uses a nitrogen purge to displace SO2 from the sample, absorption of the gas in a measured iodine solution, and titration of excess iodine with standard sodium thiosulfate.

Key topics and requirements

Scope: Intended for sulphuric acid and oleums with SO2 ≥ 2 mg/kg. (Note: for much higher SO2 levels, ISO/R 912 is referenced.)
Principle: Displace SO2 from a weighed test portion with a stream of pure nitrogen, absorb released SO2 in a known volume of iodine solution, then titrate excess iodine with standard sodium thiosulfate (iodometric/iodometric titration).
Apparatus:
- Three-neck glass flask (250 or 500 ml) with a stoppered funnel and a central tube fitted with a fritted glass disperser.
- Series of three Drechsel-type absorber bottles (100–125 ml) for iodine absorption and to trap entrained iodine.
- Glass stoppered sample bottle, flowmeter or bubble counter for gas flow measurement.
Reagents:
- Iodine solution (approx. 0.01 N, 0.05 N or 0.1 N depending on expected SO2).
- Standard sodium thiosulfate titrant matching iodine strength.
- Starch indicator (5 g/L) and hydrazine sulfate (used if nitrite/nitrate ions are present).
- High-purity nitrogen (oxygen

Related standards

Other ISO standards

Overview

Key topics and requirements

Scope: Intended for sulphuric acid and oleums with SO2 ≥ 2 mg/kg. (Note: for much higher SO2 levels, ISO/R 912 is referenced.)
Principle: Displace SO2 from a weighed test portion with a stream of pure nitrogen, absorb released SO2 in a known volume of iodine solution, then titrate excess iodine with standard sodium thiosulfate (iodometric/iodometric titration).
Apparatus:
- Three-neck glass flask (250 or 500 ml) with a stoppered funnel and a central tube fitted with a fritted glass disperser.
- Series of three Drechsel-type absorber bottles (100–125 ml) for iodine absorption and to trap entrained iodine.
- Glass stoppered sample bottle, flowmeter or bubble counter for gas flow measurement.
Reagents:
- Iodine solution (approx. 0.01 N, 0.05 N or 0.1 N depending on expected SO2).
- Standard sodium thiosulfate titrant matching iodine strength.
- Starch indicator (5 g/L) and hydrazine sulfate (used if nitrite/nitrate ions are present).
- High-purity nitrogen (oxygen

ISO 3423:1975 PDF

Technical details

Abstract

Overview

Key topics and requirements

Related standards

Abstract

Overview

Key topics and requirements

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