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Ref. NO. : ISO/R Y12-1Y68 (E)
UDC 661.25 : 543.21
IS0
I N TERN AT1 ON A L O R G A N I Z AT1 O N FOR S TA N DA RD IZATIO N
IS O R ECO M M EN DATI O N
SULPHURIC ACID AND OLEUM FOR INDUSTRIAL USE
DETERMINATION OF SULPHUR DIOXIDE CONTENT
BARIUM SULPHATE GRAVIMETRIC METHOD
1st EDITION
December 1968
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian.
Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 9 12, Sulphuric acid and uleum fur industrial use -- Determination of’ sulphur
dioxide content ~ Barium sulphate gravimetric method, was drawn up by Technical Committee iSO/TC 47, Chemistry,
the Secretariat of which is held by the Ente Nazionale ltaliano di Unificazione (UNI).
Based on detailed work on this question carried out by the Technical Committee, a Draft 1SO Recommendation
was adopted in 1965.
In June 1967. this Draft IS0 Recommendation (No. 1187) was circulated to all the IS0 Member Bodies for
enquiry. It was approved, subject to a few modifications of an editorial nature, by the following Member Bodies :
Austria India South Africa, Rep. of
Belgium Iran Spain
Brazil Ireland Switzerland
Chile Italy Thailand
Cuba Japan Turkey
Czechoslovakia Netherlands U.A.R.
France New Zealand U.S.S.R.
Germany Poland Yugoslavia
Hungary
Portugal
ICAITI* Romania
One Member Body opposed the approval of the Draft
United Kingdom
The Draft IS0 Recommendation was then submitted by correspondence to the LSO Council, which decided,
in December 1968, to accept it as an IS0 RECOMMENDATION.
*
Institut0 Centroamericano de lnvestigacion y Tecnologia lndustrial (Costa Rica, Guatemala, Honduras, Nicaragua, El Salvador,
Panama).
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ISO/R 912-1968 (E)
I SO Recommendat ion R 912 December 1968
SULPHURIC ACID AND OLEUM FOR INDUSTRIAL USE
DETERMINATION OF SULPHUR DIOXIDE CONTENT
BARIUM SULPHATE GRAVIMETRIC METHOD
1. SCOPE
This IS0 Recommendation describes a gravimetric method for the determination of sulphur dioxide content
of sulphuric acid and oleum for industrial use.
2. FIELD OF APPLICATION
The method is applicable to the determination of SO2 content higher than 0.005 of sulphuric acid
(m/m
and oleum for industrial use.
3. PRINCIPLE
Displacement of the sulphur dioxide present by means of a current of pure nitrogen and absorption in a sodium
hydroxide solution containing hydrogen peroxide.
Determination of the sulphuric acid by precipitation as barium sulphate in dilute hydrochloric acid.
Separation of the precipitate, ignition at 600 to 800 "C and weighing.
4. REAGENTS
Distilled water or water of equivalent purity should be used in the test.
4.1 Nitrogen, pure.
4.2 Hydrogen peroxide, 30 g/l solution, free from sulphate ions.
4.3 Hydrochloric acid, approximately d = 1.18,37 (m/m) or 12 N solution, free from sulphate ions.
4.4 Barium chloride, dihydrate (BaC12 .2H2 O), 100 g/l solution.
4.5 Silver nitrate, 5 g/l solution.
Dissolve 0.5 g of silver nitrate in water and dilute to 100 ml.
4.6
Potassium permanganate, approximately O. 1 N solution.
4.7
Sodium hydroxide, approximately O. 1 N solution.
4.8 Litmus paper.
4.9 Sulphuric acid, approximately d = 1.84,96 (m/m) or 36 N solution.
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ISO/R 912-1968 (E)
500 ml, three-necked, round-bottomed flask.
200 ml, graduated separating funnel fitting into one of the three necks of the flask.
Tube with cock, inserted into the central neck of the flask, extending about 1 cm from the bottom of the flask. The end of
the tube is fitted with a sintered glass diaphragm.
Three-way cock.
Four wash-bottles (El, Ez, E3, E4), capacity 100 ml, fitted with a sintered glass diaphragm (porosity 3 to 15 pm) at the end
of the immersion tube, for gas distribution. One branch of the cock (D) is connected to the third neck of the round-bottomed
flask (
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