This standard specifies the method for determining the content of sodium hydroxide and sodium carbonate in industrial sodium hydroxide. GB/T 4348.1-2000 Determination of the content of sodium hydroxide and sodium carbonate in industrial sodium hydroxide GB/T4348.1-2000 Standard download decompression password: www.bzxz.net

GB/T4348.1—2000
This standard is equivalent to ANSI/AWWAB501—1993 "Sodium Hydroxide" (caustic soda). The main technical differences between this standard and ANSI/AWWAB501--1993 are: in order to make the sample more scientific and representative, this standard increases the sample weight: solid alkali is 36g ± 1g, liquid alkali is 50g ± 1g; when determining the content of sodium hydroxide, the amount of barium fluoride solution added is different: ANSI/AWWAB501-1993 is 5ml, this standard is 10 mL;
When determining NaOH and Na2CO:, the volume of the sample solution is different: ANSI/AWWAB501-1993 is 100mL, this standard is 50ml. Www.bzxZ.net
The differences between this standard and GB/T4348.1-1984 "Determination of sodium hydroxide and sodium carbonate content in industrial sodium hydroxide" are as follows: The original standard weighing amount: solid alkali is 38g ± 1g, liquid alkali is 50g; this standard: solid alkali is 36g ± 1g, liquid alkali is 50g ± 1g; the original standard addition amount of barium fluoride solution when determining the content of NaOH is 20mL; this standard is 10mL; when determining the content of NazCO, the original standard uses methyl orange as an indicator; this standard uses bromocresol green-methyl red as an indicator. Determination of Na2CO: The original standard allowable difference: solid sample is 0.05%, liquid sample is 0.030%; this standard is unified as 0.05%
This standard replaces GB/T4348.1-1984 from the date of implementation. This standard is proposed by the former Ministry of Chemical Industry of the People's Republic of China. This standard is under the jurisdiction of the Chlor-Alkali Branch of the National Technical Committee for Chemical Standardization. This standard was jointly drafted by Jinxi Chemical Research Institute, Inner Mongolia Mengxi Lian Chemical Co., Ltd. and Shanghai Chlor-Alkali Chemical Co., Ltd.
The main drafters of this standard are Li Furong, Ma Wenyuan, Hu Liming, Cao Jianfang and Chen Peiyun. This standard was first issued in 1984.
1 Scope
National Standard of the People's Republic of China
Determination of sodium hydroxide and sodium carbonate content in sodium hydroxide for industrial use
Sodium hydroxide for industrial use-Determination of sodium hydroxide and sodium carbonate content This standard specifies the method for determining the content of sodium hydroxide and sodium carbonate in sodium hydroxide for industrial use 2 Referenced standards
GB/T 4348.1—2000
Replaces GB/T4348.1—1984
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard was published, the versions shown were all valid. All standards are subject to revision. Parties using this standard should explore the possibility of using the latest version of the following standards. GB/T601~1988 Preparation of standard solutions for chemical reagent determination and analysis (volume analysis) GB/T603-1988 Preparation of preparations and products used in chemical reagent test methods GB/T6682-1992 Specifications and test methods for water used in analytical laboratories (neqISO3696:1987) 3 Principle
3.1 Principle of determination of sodium hydroxide content
Barium chloride is first added to the sample solution to convert sodium carbonate into carbonic acid precipitate, and then phenolic acid is used as an indicator and titrated to the end point with hydrochloric acid standard titration solution. The reaction is as follows:
Na2CO:+BaCl2 →BaCO, +2NaClNaOH+HCl →NaC1-+-H2O
3.2 Principle of determination of sodium carbonate content
The sample solution is titrated to the endpoint with a mixed indicator of bromocresol green-methyl red and a standard hydrochloric acid solution. The total of sodium hydroxide and sodium carbonate is measured, and then the sodium hydroxide content is subtracted to obtain the sodium carbonate content. 4 Reagents and materials
The reagents and water used in this method, unless otherwise specified, refer to analytical reagents and grade 3 water (without carbon dioxide) specified in GB/T6682.
The standard solutions, preparations and products required in the test, unless otherwise specified, are prepared in accordance with the provisions of GB/T601 and GB/T603. 4.1 Standard hydrochloric acid titration solution: c(HCI)=1.000 mol/L. 4.2 Chlorination solution: 100g/L.
Before use, use phenolphthalein (4.3) as an indicator and adjust to a slightly reddish color with a sodium hydroxide standard solution. 4.3 Phenol indicator: 10 g/L.
4.4 Bromocresol green-methyl red mixed indicator: Mix three portions of 0.1 g/L bromocresol green ethanol solution and one portion of 0.2 g/L methyl red ethanol solution.
Approved by the State Administration of Quality and Technical Supervision on July 31, 2000, 98
Implemented on March 1, 2001
5 Instruments and equipment
General laboratory instruments and magnetic stirrer. 6 Analysis steps
6.1 Preparation of sample solution
GB/T 4348.1—2000
Use a dry and clean weighing bottle of known mass to quickly transfer 36g±1g of solid sodium hydroxide or 50g±1g of liquid sodium hydroxide (accurate to 0.01g) from the sample bottle. Place the weighed sample in a 1000mL volumetric flask containing about 300mL of water, rinse the weighing bottle, and add the washing liquid to the volumetric flask. After cooling to room temperature, dilute to the scale and shake well. 6.2 Determination of sodium hydroxide content
Measure 50.00mL of sample solution, inject it into a 250mL stoppered conical flask, add 10mL of barium chloride solution, add 2 to 3 drops of phenolic acid indicator, and titrate with hydrochloric acid standard titration solution under magnetic stirring until a slightly reddish end point. Record the volume of standard titration solution consumed in the titration as V1.
6.3 Determination of sodium hydroxide and sodium carbonate content Take 50.00mL of the sample solution and inject it into a 250mL stoppered conical flask. Add 10 drops of bromophenol green and bromophenol red mixed indicator. Stir with a magnetic stirrer and titrate with a hydrochloric acid standard titration solution until the end point is wine red. The volume of the standard titration solution consumed in the titration is recorded as V2.
7 Expression of analytical results
7.1 The sodium hydroxide (NaOH) content X expressed in mass percentage is calculated according to formula (1): Xi (%) = E: ViX 0. 040 00
X 100 80.00 X
m X 50/1 000
Where: c—actual concentration of hydrochloric acid standard titration solution, mol/L; V~—volume of hydrochloric acid standard titration solution consumed in the determination of sodium hydroxide, mLm
Mass of the sample, g:
(1)
0.04000—-Mass of sodium hydroxide (NaOH) in grams equivalent to 1.00 mL of standard hydrochloric acid titration solution (c(HCl)=1.000 mol/L1).
7.2The content of sodium carbonate (Na2CO.) in mass percentage X is calculated according to formula (2): X(%) - =X0052 9 × 100 - 105. 98 ×m X 50/1 000
Wherein: c -
Actual concentration of standard hydrochloric acid titration solution, mol/L; -Volume of standard hydrochloric acid titration solution consumed by measuring sodium hydroxide, mLc(V, - V)
V2--The volume of standard hydrochloric acid solution consumed by measuring sodium hydroxide and sodium carbonate, mL; the mass of the sample, g;
The mass of sodium carbonate (NaCO3) expressed in g equivalent to 1.00mL standard hydrochloric acid solution c(HCl)=1.000mol/L).
7.3 Allowable difference
The absolute value difference of parallel determination results shall not exceed the following values: sodium hydroxide (NaOH): 0.1%;
sodium carbonate (NaCO3) 0.05%.
Take the arithmetic mean of the parallel determination results as the reported result. 99
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