ISO/R 2051:1971

Title missing - Legacy paper document

General Information

• Status: Withdrawn
• Publication Date: 31-Dec-1970
• Technical Committee: ISO/TMBG - Technical Management Board - groups
• Drafting Committee: ISO/TMBG - Technical Management Board - groups
• Current Stage: 9599 - Withdrawal of International Standard
• Completion Date: 01-Jan-1976

Standards Content (Sample)

Ref. NO. : ISO/K 2051 -1971 (I.)
UDC 661.832.321 : 546.32 : 543.21
IS0
I N T E RN AT1 O N A L ORGAN IZ AT 1 ON FOR STAN DARD IZATl ON
IS0 RECOMMENDATION
R 2051
POTASSIUM CHLORIDE FOR INDUSTRIAL USE
DETERMINATION OF POTASSIUM CONTENT
GRAVIMETRIC METHOD AS POTASSIUM TETRAPHENYLBORATE
1st EDITION
August 1971
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 ----------------------
-3-
BRIEF HISTORY
The IS0 Recommendation R 205 1, Potassium chloride for industrial use ~ Determination of potassium content -
Gravimetric method as potassium tetraphen.ylborate. 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 to the adoption of Draft IS0 Recommendation No. 2051, which was circulated to
all the IS0 Member Bodies for enquiry in July 1970.
The Draft 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
Israel Switzerland
Chile
Czechoslovakia Italy Thailand
Korea, Rep. of U.A.R.
France
Germany Netherlands United Kingdom
Greece New Zealand U.S.A.
Hungary Poland U.S.S.R.
The following Member Body opposed the approval of the Draft :
Portugal
This Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council, which decided
to accept it as an IS0 RECOMMENDATION.

---------------------- Page: 2 ----------------------
J

---------------------- Page: 3 ----------------------
5-
ISOiR 2051-1971 (E
~~~~ ~ ~ ~
I SO Reco rn rnen da t i on R 2051 August 197 1
POTASSIUM CHLORIDE FOR INDUSTRIAL USE
DETERMINATION OF POTASSIUM CONTENT
GRAVIMETRIC METHOD AS POTASSIUM TETRAPHENYLBORATE
1. SCOPE
This IS0 RecommenLdtion describes a gravimetric method for the determination of potassium in potassium chloride
for industrial use.
2. FIELD OF APPLICATION
The method described is applicable to the determination of potassium in potassium chloride for industrial use,
i.e. in a product containing a minimum of about 95 % KCI. This limit, expressed convention,llly as K or K20,
corresponds to approximately 50 70 or 60 % , respectively.
3. PRINCIPLE
Dissolution of a test portion taken from the laboratory sample, previously ground and sifted.
Addition of formaldehyde to transform any ammonium ions present into hexamethylenetetramine and of the disodiur
salt of ethylenediamine tetra-acetic acid to complex any extraneous cations present which could cause excess errors.*
Precipitation of the potassium by sodium tetraphenylborate in a weakly alkaline medium.
Drying and weighing of the precipitate.
4. REAGENTS
Distilled water or water of equivalent purity should be used in the test.
4.1 Sodium hydroxide, approximately 400 g/1 solution.
4.2 Disodium salt of ethylenediamine tetra-acetic acid (EDTA) 40 g/1 solution.
Dissolve 40 g of disodium ethylenediamine tetra-acetate dihydrate in water and dilute to 1000 ml.
4.3 Sodium tetraphenylborate, alkaline solution.
Dissolve 32.5 g of sodium tetraphenylborate in 480 ml of water. Add 2 ml of sodium hydroxide solution (4.1
and 20 ml of magnesium chloride (MgC12 -6H2 O) 100 g/l solution. Stir with a magnetic stirrer for 15 minutes
and filter through a fine grain fdter.
Replace this reagent each week and fdter immediately before use.
*
These additions, which make the method of very general application, in no case have a detrimental effect on its precision or
reproducibility .

---------------------- Page: 4 ----------------------
-6- ISO/R 2051-1971 (E
Wash solution (saturated solution of potassium tetraphenylborate).
4.4
Precipitate 0.5 g of potassium tetraphenylborate in a solution of pure potassium chloride; filter it and wash
with distilled water. Bring the precipitate back into suspension in 5 litres of water and shake for about 1 hour.
Immediately before use, filter the quantity of reagent required for the determination.
Formaldehyde, 30 % (m/m) solution.
4.5
Filter before use.
4.6 Phenolphthalein, 5 g/1 ethanolic solution.
Dissolve 0.5 g of phenolphthalein in 100 ml of 95 % (V/V) ethanol.
5. APPARATUS
Ordinary leboratory apparatus and
5.1 Filter crucible, glass or porcelain, base having a pore diameter of 10 to 20 pm.
6. PROCEDURE
6.1 Preparat
...