Some standard content:
National Standard of the People's Republic of China
Working chemical
Silver nitrate
GB 12595---90
This reagent is colorless and transparent crystal, soluble in water, stable in pure and dry air, and turns black when encountering organic matter. Molecular formula: AgNO3
Relative molecular mass: 169.87 (according to the international atomic weight in 1987) Subject content and scope of application
This standard specifies the technical requirements, test methods, inspection rules, packaging and marking of working standard reagent (volume) silver nitrate. This standard is applicable to the inspection of working standard reagent (volume) silver nitrate with a content of 99.95% to 100.05%. 2 Reference standards
GB 601
GB 619
Chemical reagents-Preparation of standard solutions for titration analysis (volume analysis) Chemical reagents-Preparation of standard solutions for determination of impurities Chemical reagents
Chemical reagents
Chemical reagents
GB 6682
GB 9723
Preparation of preparations and products used in test methods General method for determination of pH color range of acid-base indicators Sampling and acceptance rules
Laboratory water specifications
Chemical reagents Flame atomic absorption spectrometry General rules GB10737 Working standard reagent (capacity) Weighing Potentiometric titration General rules HG3-119 Chemical reagent packaging and marking
HG3-1168 Preparation and determination method of chemical reagent clarity standards 3 Technical requirements
3.1 Silver nitrate (AgNO3) content, %: 99.95~100.05. 3.2 Appearance: qualified.
3.3 Aqueous solution reaction: qualified.
3.4 Maximum impurity content, %:
Clarity test, No.
Loss on drying
No precipitation in hydrochloric acid
Approved by the State Administration of Technical Supervision on 1990-12-18 Working standard (capacity)
Implemented on 1991-12-01
Chloride (C1)
Sulfate (SO,)
Iron (Fe)
Copper (Cu)
Lead (Pb)
4 Test method
12595—90
Working standard (capacity)
The standard solution for titration analysis, standard solution for impurity determination, preparations and products used in the test method and pH buffer solution shall be prepared in accordance with the provisions of GB601, GB602, GB603 and GB604. The water used in the experiment shall comply with the third-grade water specifications in GB6682. 4.1 Determination of silver nitrate (AgNO) content
Weigh 0.5g of the sample after the drying loss determination, accurate to 0.00001g, place it in a reaction bottle, dissolve it in 70mL of water, add 10mL of starch solution (10g/L), use a 216-type silver electrode as the indicator electrode, and a 217-type double salt bridge saturated calomel electrode (with saturated potassium nitrate solution in the outer salt bridge sleeve) as the reference electrode. According to the provisions of GB10737, titrate to the end point with a sodium fluoride standard solution [c(NaCl)=0.1mol/kg]. The sodium chloride standard solution (c(NaCl)-0.1 mol/kg) is prepared by weight method using the first standard reagent (volume) sodium chloride [see Appendix A (Supplement)], and the relative error of its concentration shall not be greater than 1×10-\%. The content of silver nitrate (AgNO:) is calculated according to formula (1): X = m*cX 0.16987 × 100
Wherein: x
% content of silver nitrate, %;
m1—mass of sodium chloride standard solution, 8; G
0.16987-
concentration of sodium chloride standard solution, mol/kg; (1)
mass of silver nitrate expressed in grams equivalent to 1.0000g sodium chloride standard solution (c(NaCl)=1.0000mol/kg);
mass of the sample, nom.
Note: ① mlm2 in formula (1) should be corrected for buoyancy according to the provisions of Appendix B (Supplement) of GB10737 before being substituted into the formula. ②The density of silver nitrate is 4.45g/cm2.
4.2 Appearance determination
Colorless or white crystals, no dark color. 4.3 Aqueous solution reaction determinationbzxZ.net
4.3.1 Preparation of methyl red indicator solution (0.4g/L) Weigh 0.40g of methyl red, dissolve it in 95% ethanol, and dilute it to 1000mL with 95% ethanol. 4.3.2 Determination method
Weigh 2g of sample, accurate to 0.01g, dissolve it in 20mL of water without carbon dioxide, add 1 drop of methyl red indicator solution (0.4g/L), shake well, the red color should not be darker than the pH5.0 standard, or the yellow color should not be darker than the pH6.0 standard.
The standard is to take 20mL of pH5.0 buffer solution or 20mL of pH6.0 buffer solution, add 1 drop of methyl red indicator solution (0.4g/L), shake well. 4.4 Impurity determination
The sample must be weighed accurately to 0.01g.
4.4.1 Clarity test
Weigh 10g of sample, dissolve in 100mL of water, add 0.1mL of nitric acid solution (25%), shake well, and its turbidity shall not be greater than the clarity standard No. 2 specified in HG3--1168630
.
4.4.2 Loss on drying
GB 12595-90
Weigh 5.5g of sample, accurate to 0.0001g, place in a weighing bottle that has been weighed constant in a sulfuric acid dryer, and dry in a sulfuric acid dryer to constant weight. The sample after constant weight is retained for content determination. Loss on drying is calculated according to formula (3):
m=m2× 100
Where: X
Loss on drying, %;
Mass of the sample before drying, g;
Mass of the sample after drying constant weight, .
4.4.3 Hydrochloric acid does not precipitate
(3)
Weigh 25g of the sample, dissolve it in 200mL of water, add 0.25mL of nitric acid solution (25%), dilute to 250mL, add 4mL of nitric acid solution (25%), dilute to 400mL, boil, add 30mL of hydrochloric acid solution (20%) dropwise while stirring, heat on a water bath, continue stirring until the precipitate forms larger curd-like particles. Place in a dark place for 2h, dilute to 500mL, filter, take 400mL, place in an evaporating dish that has been constant weight at 105±2℃, evaporate to dryness, and dry in an electric oven at 105±2℃ to constant weight. Perform a blank test at the same time. The difference in the mass of the residue between the sample and the blank test shall not be greater than 1.0mg. 4.4.4 Chloride
4.4.4.1 Preparation of fluoride-free silver nitrate solution Weigh 10g of sample, dissolve in 80mL of water, add 5mL of nitric acid, dilute to 100mL, shake well. Place in a dark place for 10min, filter with chlorine-free filter paper.
4.4.4.2 Determination method
Weigh 2g of sample, dissolve in 20mL of water, add 1mL of nitric acid, dilute to 25mL, shake well, place in a dark place for 10min, and the turbidity should not be greater than the standard.
The standard is to take the impurity determination standard solution containing 0.01mg of chloride (C1) and 20mL of chloride-free silver nitrate solution, dilute to 25mL, and treat it in the same way as the sample solution of the same volume. 4.4.5 Sulfate
Weigh 1g of sample, dissolve in 20mL of water, add 0.5mL of acetic acid solution (30%). Mix 0.25mL potassium sulfate ethanol solution with 1mL saturated barium nitrate solution (seed solution), place accurately for 1min, add the above acidified sample solution, dilute to 25mL, shake well, place for 5min, the turbidity should not be greater than the standard. The standard is to take the impurity determination standard solution containing 0.02mg sulfate (SO), dilute to 20mL, and treat it in the same way as the sample solution of the same volume.
Determine according to the provisions of GB9723, where:
4.4.6.1 Instrument conditions
Light source: iron hollow cathode lamp;
Wavelength: 248.3nm;
Flame: acetylene-air.
4.4.6.2 Determination method
Weigh 25g of sample and dissolve it in 20mL of water. Add about 60mL of ascorbic acid solution (250g/L) under constant stirring until precipitation is complete. Continue stirring for 10min, filter, wash the filter residue with water, add 10mL of 30% hydrogen peroxide, dilute to 100mL, take 20mL in four portions, 1 portion without adding standard, 2, 3, 4 portions respectively add proportional standard solution, dilute to 25mL, adjust to zero with blank solution, and follow GB9723 6.2.2.
Measured in accordance with the provisions of GB9723, where:
4.4.7.1 Instrument conditions
Light source: copper hollow cathode lamp;
Wavelength: 324.7nm;
Flame: acetylene-air.
4.4.7.2 Determination method
Same as 4.4.6.2.
Measured in accordance with the provisions of GB9723, where:
4.4.8.1 Instrument conditions
Light source: lead hollow cathode lamp;
Wavelength: 283.3nm;
Flame: acetylene-air.
4.4.8.2 Determination method
Same as 4.4.6.2.
Inspection rules
Sampling and acceptance shall be carried out in accordance with the provisions of GB619. Packaging and marking
In accordance with the provisions of HG3-119, among which:
Inner packaging form: G-2;
1259590
Outer packaging form: box made of boxboard with a specification of 600g/m2, and purple electro-optical paper on the outer layer; packaging unit: Class 3.
GB12595-90
Appendix A
Preparation of reference solution
(Supplement)
The balance and magnetic code used in the preparation of reference solution are all third-level balances and second-level codes. The weighing method is the substitution method. The water used should be placed in a constant temperature room in advance, and its temperature is the same as that of the constant temperature room. A1 Drying of the first reference reagent (capacity)
Dry the first reference reagent (capacity) to constant weight under the specified conditions. A2 Weighing of the sample
Calculate the amount of the first reference reagent (volume) required according to the concentration and mass of the reference solution to be prepared. Weigh the sample after constant weight in Article A1 according to the above calculation amount, and correct the buoyancy of the sample according to the formula in Appendix B of GB10737.
A3 Dissolution of the sample
Put the sample weighed in Article A2 in a beaker, add a small amount of water to dissolve it, and place it in a constant temperature room for 1~2 hours. A4 Preparation of the reference solution
Take a dry volumetric flask and weigh it. After weighing, transfer the solution obtained in Article A3 to the volumetric flask, add water to a slightly less mass than the mass of the solution to be prepared, weigh it, add a small amount of water, continue weighing, repeat several times, until the required mass is weighed, and mix well. The mass of the solution is corrected for buoyancy according to the formula in Appendix B of GB10738.
A5 Calculation of the concentration of the reference solution
The concentration of the reference solution is calculated as follows:
Where: c——Concentration of the reference solution, mol/kg; m
×1000
-Mass of the first reference reagent (volume) after buoyancy correction, g;-Mass of the reference solution after buoyancy correction, nom; m2
M-Relative molecular mass of the first reference reagent (volume), g/mol. Additional remarks:
This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of Beijing Chemical Reagent General Factory. This standard was drafted by Beijing Chemical Factory. The main drafters of this standard are Wang Sunjue, Liu Dongni and Chen Hua. 653
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