GB/T 4120.3-1992 Determination of acidity in industrial liquid methyl chloride products Titration method GB/T4120.3-1992 standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Liquid chlorinated methanes for industrial use-Determining acidity (titrlmetry) GB/ 4120. 3-92
Replaces GR 4120.383
This standard is equivalent to the international standard ISO1393-1977 "Liquid halogenated hydrocarbons for industrial use-Determining acidity-Titrlmetry". 1 Subject content and scope of application
This standard specifies the method for determining the acidity of industrial liquid fluoroalkanes. This method is applicable to the determination of the acidity of industrial methane, industrial trifluoromethane, industrial carbon tetrafluoride and other products. 2 Reference standards
(B601 Chemical reagent titration analysis (volume analysis) Preparation of standard solution 3 Principle of the method
This method is based on the use of water to extract the acid contained in the sample, using bromocresol green as an indicator and titrating with sodium hydroxide standard titration solution. 4 Instruments
General laboratory instruments and stopwatch.
5 Reagents and solutions bzxz.net
5.1 Experimental air Use distilled water or water of equal purity to neutralize bromocresol green. In a container filled with distilled water, add 58 drops of 19/L bromocresol green ethanol solution per 150mL of distilled water, and neutralize with 0.01mol/L sodium hydrocyanide (or hydrochloric acid) standard titration solution until the color just changes to pure blue.
5.20.01tmnl/L. Sodium hydroxide standard titration solution: accurately dilute the 0.1mol/L. sodium hydroxide standard titration solution prepared according to GB6u1 to 0.olrmol/L sodium nitrite standard titration solution. 5.3c(HCl)=0.01mul/I. Hydrochloric acid standard titration solution: Accurately dilute the 0.1mal/1.5L hydrochloric acid standard titration solution prepared according to GB601 to 0.01mal/L hydrochloric acid standard titration solution. 5.41g/L bromocresol green ethanol solution: weigh 0.1g bromocresol green, dissolve it in 95% (V/V) ethanol, and then dilute to 100mL. 6 Analysis procedures
6.1 According to the degree of concentration of the laboratory sample, take 20~80ml of sample in the measuring tube. 6.2 Determination
Measure 40mL of distilled water that is neutral to bromocresol green and put it in the measuring tube with the sample added. , after 3 minutes of digging, separate the bottom layer of the sample by static sliding, and keep the water layer for later use.
National Technical Supervision Commission approved on April 24, 1992 and implemented on 199302-01
GB/T4120.3--92
Use a base to measure 30ml of the extract. Put it in a 100mL conical flask. If the indicator is insufficient, add 1 to 2 drops. Use 0.01mol/l sodium hydroxide standard titration solution to titrate. The end point is when the color of the titration changes to pure blue. 6.3 Calculation
The acid content (%·in HCI) in the sample is calculated as follows: = × . 036 16 × 100
Wherein: (Na01l)--
the actual concentration of the substance in the standard titration solution of sodium oxychloride.nmol/L; V-: the volume of the standard titration solution of sodium hydroxide consumed by the sample during titration, mLV-the volume of the sample.mL;
a--the density of the sample.g/em,
the mass of 0.036 46
hydrochloric acid in grams equivalent to 1.00mL of the standard titration solution of sodium hydroxide [c(NaOH)-1.000mol/L).
7The allowable difference
The difference between the results of two determinations shall not exceed 0.3×10-1%, and the arithmetic mean shall be taken as the test result. Additional remarks:
This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China and is under the jurisdiction of the Beijing Institute of Chemical Industry of the Ministry of Chemical Industry. This standard was drafted by Beijing Chemical Research Institute of the Ministry of Chemical Industry, Zigong Honghe Chemical General Factory and Shanghai Electrochemical. The main drafters of this standard are Li Lanqing, Wei Changjie, Yang Junqing, Tang Guoqiang and Liao Shengchai.
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