YS/T 910-2013 English PDF (YST910-2013)

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YS/T 910-2013: Determination of copper content for brass. lodimetry
YS/T 910-2013
NON-FERROUS METAL INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 77.120.30
H 13
Determination of copper content for brass - Iodimetry
ISSUED ON: OCTOBER 17, 2013
IMPLEMENTED ON: MARCH 01, 2014
Issued by: Ministry of Industry and Information Technology of the People's
Republic of China
Table of Contents
Foreword ... 3 
1 Scope ... 4 
2 Method summary ... 4 
3 Reagents ... 4 
4 Specimen ... 6 
5 Analysis steps ... 6 
6 Calculation of analysis results ... 7 
7 Precision ... 7 
8 Test report ... 8 
Determination of copper content for brass - Iodimetry
1 Scope
This Standard specifies the method to determine the copper content in brass.
This Standard applies to the determination of copper content in brass. Determination
range: 50.00%~97.00%.
This Standard is not intended as a method of arbitration.
2 Method summary
The specimen is dissolved in nitric acid. Trivalent arsenic and antimony are oxidized
with bromine. The pH value of the control solution is 3~4. Use ammonium bifluoride
to mask iron. Add potassium iodide to act with divalent copper. The precipitated iodine
is indicated by starch. Use sodium thiosulfate standard titration solution to titrate.
3 Reagents
Unless otherwise specified, it shall only use the confirmed analytically-pure reagents
AND distilled water or deionized water or equivalent-pure water in analysis.
3.1 Ammonia (ρ=0.90g/mL).
3.2 Potassium iodide solution (100g/L).
3.3 Nitric acid (1+2).
3.4 Glacial acetic acid (ρ=1.05 g/mL).
3.5 Hydrofluoric acid (ρ=1.13 g/mL).
3.6 Ammonium bifluoride saturated solution: store in polyethylene bottles.
3.7 Bromine saturated solution.
3.8 Potassium thiocyanate solution (200g/L).
3.9 Starch solution (5g/L).
Preparation: Weigh 5g of soluble starch. Slowly add to 1L of distilled water. Stir and
mix well. Boil until the solution is transparent.
3.10 Standard titration solution of sodium thiosulfate [c(Na2S2O3·5H2O) ≈ 0.1mol/L].
3.10.1 Preparation
Weigh 250g of sodium thiosulfate (Na2S2O3·5H2O). Dissolve in a 1000mL beaker. Add
2g of anhydrous sodium carbonate. Transfer to a 10L brown reagent bottle. Use freshly
boiled cooled distilled water to dilute to about 10L. Shake well. Let stand for more than
10d.
3.10.2 Calibration
Weigh three portions of 0.30g (accurate to 0.0001g) of treated pure copper sheet (mass
fraction is ≥99.95%). Determine simultaneously with the specimen according to
5.3.1~5.3.4. Carry out a blank test along with the calibration.
NOTE: Processing of pure copper sheets: Put the pure copper sheet into slightly boiling glacial
acetic acid (1+4) and boil for 1min. Rinse twice with water and absolute ethanol after removal. Bake
in a 100℃ oven for 4min. Cool down. Store in a ground-mouth reagent bottle for later use.
Calculate the actual concentration of sodium thiosulfate standard titration solution
according to formula (1):
Where,
c - Actual concentration of the standard titration solution of sodium thiosulfate, in moles
per liter (mol/L);
w - Mass fraction of copper in pure copper sheet, %;
m - Mass of pure copper sheet, in grams (g);
V1 - Volume of sodium thiosulfate standard titration solution consumed by titration of
pure copper solution during calibration, in milliliters (mL);
V0 - Volume of sodium thiosulfate standard titration solution consumed by titrating
copper blank solution during calibration, in milliliters (mL);
63.55 - Molar mass of copper, in grams per mole (g/mol).
3.11 Parallel calibration
Conduct parallel calibration in triplicate. When the relative error of the measured value
is not more than 0.1%, take the average value; otherwise re-calibrate.
NOTE: The sodium thiosulfate standard titration solution must be re-calibrated every other week.