|
IS0
IN TERN AT1 ON A L ORGAN IZATl O N FOR STAN DARD I Z AT1 O N
IS0 RECOMMENDATION
R 995
POTASSIUM HYDROXIDE FOR INDUSTRIAL USE
DETERMJNATION OF SILICA CONTENT
GRAVIMETRIC METHOD BY INSOLUBI LlZATlON
1st EDITION
February 1969
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.
---------------------- Page: 1 ----------------------
BRIEF HISTORY
The IS0 Recommendation R 995, Potassium hydroxide for industrial use - Determination of silica
content - Gravimetric method by insolubilization, was drawn up by Technical Committee iSO/TC 47, Chemistry,
the Secretariat of which is held by the Ente Nazionale Italian0 di Unificazione (UNI).
Work on this question led, in 1966, to the adoption of a Draft IS0 Recommendation.
In December 1966, this Draft IS0 Recommendation (No. 1104) was circulated to all the IS0 Member
‘c, ’-
Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature, by the following
Member Bodies :
Austria Ireland South Africa, Rep. nf
Belgium Israel Spain
Brazil Japan Switzerland
C‘hile Korea, Dem. P. Rep. of Thailand
Cuba Netherlands Turkey
U.A.R.
Czechoslovakia New Zealand
United Kingdom
Germany Poland
U.S.S.R.
Hungary Portugal
India Romania Yugoslavia
Three Member Bodies opposed the approval of the Draft :
France
Italy
U.S.A.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council, which
L decided, in February 1969, to accept it as an IS0 RECOMMENDATION.
---------------------- Page: 2 ----------------------
I’
---------------------- Page: 3 ----------------------
ISO/R 995-1969 (E
February 1969
IS0 Recommendation R 995
POTASSIUM HYDROXIDE FOR INDUSTRIAL USE
DETERMINATION OF SILICA CONTENT
GRAVIMETRIC METHOD BY INSOLUBILIZATION
1. SCOPE
This IS0 Recornmendation describes a gravimetric method by insolubilization for the determination of silica
content in potassium hydroxide for industrial use.
2. FIELD OF APPLICATION
The method is applicable to the determination of silica (SiO,) content greater than or equal to 0.01
(m/m)
calculated on KOH.
3. PRINCIPLE
lnsolubilization of silica by evaporation to dryness of the test portion, previously dissolved and acidified (by
means of hydrochloric acid).
Solution of the soluble salts and filtration of the insoluble matter containing silica. Washing, recovery of silica
contained in the filtrate and washings, filtration, washing, drying, ignition and weighing of the insoluble matter.
After treatment with hot hydrofluoric and sulphuric acids to remove the silica. further ignition and weighing.
The difference in mass represents the silica present in the test portion.
4. REAGENTS
Distilled water or water of equivalent purity should be used in the test.
4.1 Hydrochloricacid, approximately d = 1.19, 38 (m/m) or 12 N solution.
4.2 Hydrofluoric acid, approximately d = 1.15, 40 (m/m) solution.
Sulphuric acid, approximately d = 1.18, 25 (m/m) or 6 N solution.
4.3
4.4 Silver nitrate, 5 g/1 nitric solution.
0.5 g of silver nitrate in a small amount of water, add 10 ml of approximately d = 1.4 nitric acid
Dissolve
solution and dilute to 100 ml.
4.5 Methyl orange, 0.5 g/l solution.
Dissolve 0.05 g of methyl orange in water and dilute to 100 ml.
-5-
-----------------
...