Sodium tungstate sodium molybdate mixed solution

Beijing Huakesheng Fine Chemical Products Trading Co., Ltd. produces and sellsSodium tungstate sodium molybdate mixed solutionSodium tungstate is an inorganic substance with the chemical formula Na2WO4. It is a colorless crystalline or white crystalline powder that loses its crystalline water when dried in air at 100 ℃. It is soluble in water and insoluble in ethanol, with a relative density of 3.23-3.25 and a melting point of 698 ℃ (anhydrous). Chinese name: Sodium tungstate:
Foreign name: Sodium Tungsten Dihydrate
Chemical formula Na2WO4
Molecular weight 293.83
CAS login number 10213-10-2
Melting point 698 ℃
Water soluble, soluble in water, insoluble in ethanol
Density 3.25 g/cm3
Appearance: Colorless crystals or white crystalline powder
Application for manufacturing metal tungsten, tungstic acid, tungstate and other content determination:
Determination of tungsten trioxide (WO3) content in sodium tungstate (Xinkoning gravimetric method)
1. Method summary: In a hot solution with a pH value of 3.00-4.4, tungstic acid is precipitated with hydrochloric acid and separated from impurities. After calcination, it becomes tungsten trioxide, which is weighed and compared by color.
2. Reagents: Methyl violet indicator 0.1%, hydrochloric acid (1+1), Xinkening hydrochloric acid solution 10% (prepared with 1+1 hydrochloric acid), Xinkening hydrochloric acid washing solution 0.2%, solid NaOH, and broad test paper.
3. Operation steps: Weigh 0.5 grams of the sample into a 250ml beaker, dissolve it in a small amount of water, add 100ml of hot water at 60-80 ℃, 2 drops of 0.1% methyl orange indicator (if the indicator is brown, add more), and neutralize it with hydrochloric acid (1+1) until it turns red. While stirring continuously, add 10ml of 10% Xinkening and continue stirring to make the sediment settle. If the upper layer is clear, let it stand still. After the sediment settles, filter it with a quick quantitative filter paper. The filtrate is received in a 250ml volumetric flask, and the sediment is washed with 0.2% Xinkening solution at least five times. After washing, the sediment is transferred to a porcelain crucible together with the filter paper, dried and carbonized on an electric furnace, and then carbonized and burned in a muffle furnace at 750-800 ℃ for 30-45 minutes, cooled, and weighed. The filtrate was subjected to tannin and methyl violet colorimetric method.
4. Calculation of analysis results: WO3 (%)=(W/G) × 100+C. In the formula: W - weight of tungsten trioxide (grams), G - weight of the sample weighed (grams), C - WO3 content measured in the filtrate.
5. Precautions:
① The precipitation must be washed away with sodium ions, otherwise the burnt material will turn black and the result will be higher.
② The indicator can be 0.1% methyl orange, at which point the filtrate can be analyzed using the thiocyanate colorimetric method.
The method is as follows: Pour the filtrate from the volumetric flask back into the beaker containing the original sample, add solid NaOH to the beaker until the pH of the filtrate is greater than 12, then pour the filtrate back into a 250ml volumetric flask, dilute to the mark, dry filter, and follow the thiocyanate spectrophotometric method.

Hazard description: Avoid contact with skin and eyes. Keep the container tightly sealed. Avoid ingestion and inhalation.

name

Chinese name: Sodium molybdate

English alias: Sodium molybdate dihydrate, Sodium molybdate, disc molybdate

trait

White crystalline powder. Losing 2 molecules of crystal water at 100 ℃. Dissolve in 1.7 parts of cold water and approximately 0.9 parts of boiling water, a 5% aqueous solution with a pH of 9.0-10.0 at 25 ℃. Relative density (d184) 3.28. Melting point 687 ℃. The median lethal dose (mouse, intraperitoneal) is 344mg/kg. It is stimulating.

store

Sealed storage.

Sodium tungstate sodium molybdate mixed solution