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IS0
I N T E R N AT I O N A L O R G A N I Z AT I O N FOR S TA N DARD 1 ZATl O N
IS0 RECOMMENDATION
R 910
SULPHURIC ACID AND OLEUM FOR INDUSTRIAL USE
DETERMINATION OF TOTAL ACIDITY AND CALCULATION
OF FREE SO, CONTENT OF OLEUM
Vo I u metric met hod
1st EDITION
December 1968
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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 10, Sulphuric acid and ohm for industrial use - Determination
of total acidity and calculation of free SO, content of oleum - Volumetric method, was drawn up by
Technical Committee ISO/TC 47, Chemistry, the Secretariat of which is held by the Ente Nazionale
Italian0 di Unificazione (UNI).
Based on detailed work on this question carried out by the Technical Committee, a Draft
IS0 Recommendation was adopted in 1965.
In June 1967, this Draft IS0 Recommendation (No. 1180) 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
Switzerland
Brazil Ireland
Thailand
Chile Italy
Turkey
Cuba Japan
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 IS0 Council,
which decided, in December 1968, to accept it as an IS0 RECOMMENDATION.
Institut0 Centroamericano de Investigacih y Tecnologia Industrial (Costa Rica, Guatemala, Honduras, Nicaragua,
El Salvador, Panama).
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ISO/R 910-1968 (E)
IS0 Recommendation R 910 Decem ber 1968
SUL "URIC ACID AND OLEUM FOR INDUSTRIAL USE
DETERM
NATION OF TOTAL ACIDITY AND CALCULATION
OF FREE SO, CONTENT OF OLEUM
Volumetric method
1. SCOPE
This IS0 Recommendation describes a volumetric method for the determination of the total acidity
of sulphuric acid for industrial use, conventionally expressed as H, SO,, and for the calculation of
free SO3 content of oieum.
2. FIELD OF APPLICATION
The method is applicable to sulphuric acid and oleum for industrial use. Two cases are considered :
2.1 H2SO4 content equal to, or lower than, 98
2.2
H, SO4 content higher than 98
3. PRINCIPLE
Preliminary oxidation with hydrogen peroxide and titration of total acidity by means of a sodium
hydroxide standard volumetric solution, in the presence of methyl red.
4. REAGENTS
Distilled water or water of equivalent purity, neutral to methyl red, should be used in the test.
4.1
Hydrogen peroxide, 60 g/l solution, neutral to methyl red.
4.2
Sodium hydroxide, N standard volumetric solution.
(see Note, section 7).
4.3 Methyl red, 1 g/1 ethanolic solution.
Dissolve 0.1 g of methyl red in 95 (v/v) ethanol and dilute to 100 ml with the same
ethanol.
5. APPARATUS
Ordinary laboratory apparatus and
5.1 Ground glass stoppered flask, capacity approximately 500 mi, with neck of about 30 mm
diame ter.
5.2 Spherical glass ampoule, of suitable shape and capacity, for example 20 mm in diameter,
having one capillary end of about 50 mm in length (see example indicated in the following
figure.
5.3 Burette, precision at least 0.05 ml.
5.4 Conicalflask, capacity 500 ml, with ground glass stopper.
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ISO/R 910-1968 (E
FIGURE - Spherical glass ampoule
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ISO/R 910-1968 (E)
6. PROCEDURE
6.1 H2S04 content equal to or lower than 98 'k
6.1.1 Test portion. In a weighing bottle, previously tared, weigh, to the nearest 0.1 mg, approxi-
mately 2 g of the test sample.
6.1.2 Determination. Transfer quantitatively the test portion (6.1.1) in a 500 ml conical flask
containing approximately 300 ml 'of water.
Add 5 ml of the hydrogen peroxide solution (4.1) and gently boil for 10 minutes.
Allow to cool, add two drops of the methyl red solution (4.3) and titrate to the end-point
by means of the sodium hydroxide solution (4.2).
6.2 H2 SO4 content higher than 98
6.2.1 Test portion. Carefully mix the test sample by shaking the container. If the acid is partially
crystallised, slightly heat the container until the sample is dissolved, then care
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