GOST 12559.1-82
GOST 12559.1−82, GOST 12559.2−82
INTERNATIONAL STANDARDS
ALLOYS, PLATINUM-IRIDIUM
METHODS OF ANALYSIS
Edition official
IPK PUBLISHING house of STANDARDS, Moscow
UDC 669.231.5'232: 543.06:006.354 Pear B59
INTERSTATE STANDARD
ALLOYS, PLATINUM-IRIDIUM
Method of determination of iridium
Platinum-iridium alloys.
Method for the determination of iridium
GOST
12559.1−82
AXTU 1709
Date of introduction 01.01.84
This standard sets the potentiometric method for the determination of iridium with the use of automatic titration unit in platano-iridium alloys (in mass fraction of iridium from 4.0 to 32.0%).
The method is based on titration of iridium with a solution of hydroquinone in hydrochloric acid medium to a predetermined value of the potential difference. The electrode pair is formed by the plane of the indicator electrode and silver chloride reference electrode.
1. GENERAL REQUIREMENTS
1.1.General requirements for method of analysis according to GOST 22864 with the following addition: the numerical value of the result of the analysis must end with a digit of the same rank as that of the normalized indicator grade composition.
(Changed edition, Rev. No. 1).
2. APPARATUS, REAGENTS AND SOLUTIONS
pH-meter laboratory.
The block automatic titration laboratory.
The magnetic stirrer.
Electrode platinum laboratory EPL-02.
Burette with automatic zero setting with a capacity of 25 cm* 1 2 3.
Crucibles porcelain № 4 according to GOST 9147.
Hydrochloric acid according to GOST 3118 and diluted 1:1.
Nitric acid according to GOST 4461.
Mixture of nitric and hydrochloric acids in a ratio of 1:3.
Hydrogen peroxide according to GOST 177, a solution with a mass fraction of 3%.
Sodium chloride according to GOST 4233, 0.1 mol/dm3, a solution of 5.8 g of salt is dissolved in 50 cm3 of water, top up with water to 1000 cm3 and stirred.
Rectified ethyl alcohol according to GOST 5962.
Iridium brand 99,9 GOST 13099.
Iridium standard solution: prepare by the method of electrolytic dissolution of iridium, as the official Edition Reprinting is prohibited
★
© Standards publishing house, 1982 © And PC Publishing house of standards, 1999 Reprint with Changes
specified in clause 3.2. When this solution passes ~ 0,7 — 0,8 g of iridium in the I h. the Solution was boiled down to 150 cm3, cooled and filtered in a volumetric flask with a capacity of 500 cm3.
A lot of iridium (L), g/cm3, calculated by the formula
y=
500 '
where /ha — weight of the plates to dissolve, g; T2 — weight plates after dilution, g;
/га3 is the mass of the insoluble residue,
Hydroquinone according to GOST 19627, 0.005 mol/dm3 solution: 0,5505 g of hydroquinone are dissolved in 20 cm3 of water, add 2 cm3 hydrochloric acid, transferred to a measuring flask with volume capacity of 1000 cm3, top up with water to the mark and mix. The solution was stored in a dark place.
The titer determination 0.005 mol/dm3 solution of hydroquinone:
5 cm3 of a standard solution of iridium is placed in a beaker with a capacity of 100 cm3, poured 10 cm3 of hydrochloric acid (1: 1), 5 cm3 of hydrogen peroxide and the solution heated in a boiling water bath for 15 min for the oxidation of iridium. The solution was cooled, poured 10 cm3 of water and titrated with a solution of hydroquinone as shown in sec. 4.
The titer of a solution of hydroquinone (7) iridiu, expressed in g/cm3, calculated by the formula
T —
1 ~ V'
where m is the mass of iridium, the corresponding aliquote part of standard solution, g;
V — volume of solution of hydroquinone consumed for titration, cm3.
(Changed edition, Rev. No. 1).
3. PREPARATION FOR ASSAY
3.1. Method of chemical dissolution of the alloy (with a mass fraction of iridium up to 15%)
A portion of the alloy with a weight of 2.5 g was dissolved with heating in 100 cm3 of the mixture of acids. The solution was boiled down to 5 cm3 of hydrochloric acid and transferred to a triple evaporation with 10 cm3 of hydrochloric acid (1:1).
3.2. Method of electrolytic dissolution (when the mass fraction of iridium from 15 to 32%)
The sample to be analyzed must be in the form of plates with a length of 90 — 100 mm, width 35 — 40 mm and thickness of 0.5 — 0.3 mm. surface of the plate is wiped with alcohol, dried, weighed, fixed in clamps, are immersed in an electrolyte of hydrochloric acid (1: 1) and dissolved by electrolytic method. Dissolution produces alternating current at a current of 50 A for 3 h. the solution goes from 2.3 to 2.7 g of alloy.
During dissolution it is necessary to periodically add fresh portions of the electrolyte. After reconstitution, the current is turned off, Unscrew the plate, washed with water, dried and weighed. The difference in weight of plates before and after dissolution, the solution corresponds to the mass of the alloy. The solution of the alloy is evaporated to 50 cm3, cooled and filtered. Nearshoring the residue calcined in a tared crucible, reduced in a current of hydrogen and weighed. Mass of undissolved residue is subtracted from the mass of the solution of the alloy.
4. ANALYSIS
Prepared for analysis the analyzed alloy solution is transferred into a measuring flask with a capacity of 250 cm3, was adjusted to the mark with water and mix.
Of take volumetric flasks pipette two aliquots of 10 cm3, which are placed in cups with a capacity of 100 cm3, poured 10 cm3 of hydrochloric acid (1: 1), 5 cm3 of hydrogen peroxide and the solution heated in a boiling water bath for 15 min for the oxidation of iridium. The solution was cooled, poured 20 cm3 of sodium chloride solution and titrated by potentiometric method with a solution of hydroquinone to a predetermined potential difference on the block automatic titration is equal to 500 mV, when the width of the zone of pulse 200 mV and exposure time of 10 seconds.
5. PROCESSING OF THE RESULTS
5.1. Mass fraction of iridium (X) in percent is calculated by the formula
v v — T■ 100 l 9
m
where V is the volume of a solution of hydroquinone consumed for titration, cm3;
T — titer of a solution of hydroquinone in iridiu, g/cm3, m is the mass of the alloy, the corresponding aliquote part of the solution,
5.2. Allowable absolute discrepancies in the results of parallel measurements (d — metric convergence) at a confidence probability P= 0,95 shall not exceed 0.20%, the mass fraction of iridium is 10% and of 0.30% when the mass fraction of iridium in excess of 10%.
Absolute differences average results of determinations obtained in two different laboratories (23 — an indicator of reproducibility) shall not exceed 0,30% when the mass fraction of iridium is 10% and 0.45% when the mass fraction of iridium in excess of 10%.
(Changed edition, Rev. No. 1).
5.3. Control of the correctness of the results of determining the mass fraction of iridium is performed by playback of its mass fraction in the artificial mixtures the chemical composition close to the composition of the analyzed alloy, drawn through the entire course of the analysis.
The sample analysis results are considered correct if the absolute difference between the maximum and minimum values of the mass fraction of iridium in the artificial mixture does not exceed 0.15% when the mass fraction of iridium from 4.5 to 10.0% and 0.28% for the mass concentration of iridium in excess of 10.0%.
(Added, Rev. No. 1).
INFORMATION DATA
1. DEVELOPED AND INTRODUCED by the Ministry of nonferrous metallurgy of the USSR
DEVELOPERS
A. A. Kuranov, N. And. Timofeev, G. S. HAK, N. With. Stepanov, D. I. Sergienko, L. A., Snitko, T. I. Belyaev, E. E. Safonova
2. APPROVED AND WHEN INTO EFFECT by Decision of the USSR State Committee for
standards from
3. REPLACE GOST 12559−67 in part of sec. 2.
4. REFERENCE NORMATIVE AND TECHNICAL DOCUMENTS
5.Limitation of actions taken by Protocol No. 3−93 Interstate Council for standardization, Metrology and certification (ICS 5−6-93)
The designation of the reference document referenced
Item number
177−77 GOST GOST GOST 3118−77 4233−77 GOST 4461−77 GOST 5962−67 GOST 9147−80 13099−67 GOST GOST GOST 19627−74 22864−83
Sec. 2 Sec. 2 Sec. 2 Sec. 2 Sec. 2 Sec. 2 Sec. 2 Sec. 2 1.1
6.REPRINT (March 1999) amendment No. 1, approved in June 1988 (IUS 10−88)
