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Properties and standards of chromic anhydride for chromium plating

Molecular formula: CrO3

Molecular weight: 99.99

Alias: Chromic acid, chromium anhydride, chromium oxide

Specificity: 2.7 (crystallization)

Properties: Dark red rhombic crystalline system.It breaks down slightly during melting;Chromium oxide is formed by decomposition at 195 C.Oxygen is liberated at 200-250 C to form intermediate between chromium anhydride and chromium trioxide.Peroxide is formed in the presence of ozone, chromium peroxide in the presence of hydrogen peroxide, and chromium chloride in the presence of hydrogen chloride.It is soluble in water, alcohol, sulfuric acid, ether and insoluble in acetone.Easy to tide.As a strong oxidant, friction in contact with organic substances can cause combustion.Burning or explosion occurs when alcohol or benzene is encountered.It is highly corrosive and toxic.

Usage: In addition to producing chromium compounds, it is also used as an oxidant in chemical industry, printing and dyeing industry.Mainly, such as the production of zinc chrome yellow, the production of chrome oxide green (chromium trioxide), the production of low temperature transformation catalysts (also known as low change catalysts, series of copper-zinc-chromium low change catalysts), high temperature transformation catalysts (also known as medium change catalysts or oxidation catalysts), and high pressure methanol synthesis catalysts.Used for chrome plating on bicycles, sewing machines, semi-steel watches, torches, hardware parts for daily use, instruments, instruments, etc. and chrome plating on printing drums of textile industry.It is also used for wood preservation, electropolishing (aluminium cover, aluminium box, aluminium pen) to electrolytically produce chromium metal, etc.

Standard number: GBT1610-1999

Quality standard:

Item

Indicator

Premium

First class

Qualified Products

Chromic anhydride%≥

99.7

99.5

99.0

Sulfate%≤

0.06

0.15

0.30

Water insoluble%≤

0.02

0.05

0.10

SodiumNa)%≤ 

0.05

-

-


Packaging with Chromic Anhydride: Sealed in barrels lined with plastic bags, with a net weight of 50kg or 100kg per barrel.Outside the barrel, there should be clear "oxidant" and "toxic" marks.

Cautions for storage and transportation: It belongs to secondary inorganic oxidant, hazard code number: 23001.Store in a cool, ventilated and dry warehouse.Be careful to protect against moisture, heat and direct sunlight. Storage temperature should not exceed 30 C. Containers must be sealed.Keep away from heat and fire.Containers avoid impact, vibration and friction.It is forbidden to contact flammable substances, and should not be stored and mixed with organic substances such as alcohol, benzene, flammable substances, reducing agents, strong acids, hydrogen peroxide, etc.Rain and sun protection and moisture protection are required during transportation.Care should be taken when loading and unloading to prevent the container from hitting.The storage period of industrial grade chromic anhydride products is 1 year.After the storage period has expired, it shall be checked whether it still meets the national standards before use.Water, sand and various fire extinguishers are available to fight fires.However, the solution should be prevented from flowing to flammable materials.

Toxicity and protective measures: Chromium can irritate skin and mucosa locally and cause ulceration.Inhalation of aerosols can cause cartilage perforation in the nasal septum, damage to respiratory organs, and even pulmonary sclerosis.The general toxic effects are liver, kidney, gastrointestinal tract, heart and blood system damage.When the nasal mucosa is damaged, wash it with soap and apply ointment to the nasal passage after work and before bedtime.When ulcers occur, chromium exposure should be stopped for 2 months.When it splashes onto the skin, rinse it with water immediately for 15 minutes.When eczema and dermatitis occur, topical use of ointment with no stimulating effect of lotion or powder spraying.If it falls into your eyes, rinse it with water for more than 15 minutes immediately, then drip the fish liver oil, and then drip 30% sulfonamide acetyl solution.Serious cases should be sent to the hospital for treatment immediately.The maximum allowable concentration (followed by CrO3) is 0.01mg/m3.Production equipment should be fully sealed and the workplace well ventilated to keep the concentration of chromium in the air low.Production workers wear work clothes, masks, Rubber Aprons and lactic acid gloves, and masks when aerosols are present in the air.Check-ups should be performed beforehand and reviewed every 2 years.Otolaryngology was performed every 3 supplements.

Supplementary Content: Chromic anhydride dissolves in water to form mainly chromic acid [H2CrO4] and dichromate [H2Cr2O7], which are always in dynamic balance.Dichromate, also known as pyrochromic acid or dichromate, is free.H2Cr2O7 is known to be in equilibrium with H2CrO4 in an aqueous solution of chromium oxide (VI).In this case, if the concentration of chromium oxide (VI) is low or the PH of the solution increases, the concentration of dichromate is also low.As the concentration of chromium oxide (VI) increases or PH decreases, the concentration of dichromate increases.If the concentration of chromium oxide (VI) is higher, there is H2Cr3O10 Trichromate and H2Cr4O13 tetrachromate in the solution.A mixture of H2Cr2O7 and H2CrO4 can be obtained by dissolving chromium trioxide in water, and a high content of dichromate can be obtained by acidifying the solution.It is used as a strong oxidant.


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