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Send EmailPotassium dichromate, bichromate of potash, Potassium bichromate, dichromate de potassium, Red potassium chromate, chromic acid,dipotassium salt, 7778-50-9
Potassium dichromate
CAS: 7778-50-9
Molecular Formula: Cr2K2O7
ames and Identifiers
| Name | Potassium dichromate |
| Synonyms | bichromateofpotash Potassium bichromate Potassium dichromate dichromatedepotassium Red potassium chromate chromicacid,dipotassiumsalt dichromicaciddipotassiumsalt Dichromicacid,dipotassiumsalt chromicacid(h2cr2o7),dipotassiumsalt chromicacid[h2cr2o7],dipotassiumsalt Potassium dichromate standard solution dichromicacid[h2cr2o7],dipotassiumsalt dipotassium oxido-(oxido-dioxo-chromio)oxy-dioxo-chromium |
| CAS | 7778-50-9 |
| EINECS | 231-906-6 |
| InChI | InChI=1/2Cr.2K.7O/q;;2*+1;;;;;;2*-1/rCr2O7.2K/c3-1(4,5)9-2(6,7)8;;/q-2;2*+1 |
| InChIKey | KMUONIBRACKNSN-UHFFFAOYSA-N |
Physico-chemical Properties
| Molecular Formula | Cr2K2O7 |
| Molar Mass | 294.1846 |
| Density | 7.14g/mLat 25°C(lit.) |
| Melting Point | 398 °C (lit.) |
| Boling Point | 82°C |
| Flash Point | 50°F |
| Water Solubility | 125 g/L (20 ºC) |
| Solubility | H2O: 0.1M at20°C, clear, orange |
| Appearance | powder |
| Specific Gravity | 2.676 |
| Color | Orange-red |
| Exposure Limit | ACGIH: TWA 0.0002 mg/m3; STEL 0.0005 mg/m3 (Skin)OSHA: Ceiling 0.1 mg/m3NIOSH: IDLH 15 mg/m3; TWA 0.0002 mg/m3 |
| Merck | 14,7627 |
| PH | 3.5-5.0 (25℃, 0.1M in H2O) |
| Storage Condition | Store at RT. |
| Physical and Chemical Properties | Characteristics of orange-red monoclinic or triclinic crystal system. melting point 398 ℃ relative density 2.676 solubility it is slightly soluble in cold water, easily soluble in hot water, and its aqueous solution is acidic. Insoluble in alcohol. |
| Use | Used in the manufacture of chromium chemicals, mordant, ink, glass, perfume, pigment, ceramics, varnish, explosives, medicine, etc |
Risk and Safety
| Risk Codes | R45 - May cause cancer R46 - May cause heritable genetic damage R60 - May impair fertility R61 - May cause harm to the unborn child R8 - Contact with combustible material may cause fire R21 - Harmful in contact with skin R25 - Toxic if swallowed R26 - Very Toxic by inhalation R34 - Causes burns R42/43 - May cause sensitization by inhalation and skin contact. R48/23 - R50/53 - Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment. R52/53 - Harmful to aquatic organisms, may cause long-term adverse effects in the aquatic environment. R20 - Harmful by inhalation R48/20 - R23 - Toxic by inhalation R51/53 - Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment. R22 - Harmful if swallowed R36/37/38 - Irritating to eyes, respiratory system and skin. R27 - Very Toxic in contact with skin R20/21 - Harmful by inhalation and in contact with skin. R23/24 - |
| Safety Description | S53 - Avoid exposure - obtain special instructions before use. S45 - In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) S60 - This material and its container must be disposed of as hazardous waste. S61 - Avoid release to the environment. Refer to special instructions / safety data sheets. S36/37 - Wear suitable protective clothing and gloves. S23 - Do not breathe vapour. S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. |
| UN IDs | UN 3086 6.1/PG 1 |
| WGK Germany | 3 |
| RTECS | HX7680000 |
| TSCA | Yes |
| HS Code | 28415000 |
| Hazard Class | 5.1 |
| Packing Group | III |
| Toxicity | LD50 orally in Rabbit: 90.5 mg/kg LD50 dermal Rat 1170 mg/kg |
Upstream Downstream Industry
Nature
orange-red shiny monoclinic or tri-crystalline systems. 241.6 degrees C from three to a single crystal system. Melting Point: 398 °c; About 500 °c decomposition; d25 676. Soluble in water, the concentration (%) of saturated aqueous solution at different temperatures is: 4.3 (0 ℃)11.7(20 ℃), 20.9 (40 ℃), 31.3 (60-c), 50.2(100 degrees C). The solution was acidic and insoluble in ethanol. It has strong oxidation and corrosion, and can be mixed with reducing agent, organic matter, combustible material or metal powder to form explosive mixture, which can cause combustion or explosion by friction, vibration or impact.
Preparation Method
The industrial potassium dichromate is dissolved in hot water, filtered, evaporated filtrate, cooled and rapidly stirred to obtain crystals, which are ground fine under ventilation and then dried to obtain pure potassium dichromate.
Use
Reference Reagent, trace analysis of chlorine. Also used for the determination of liver function index, redox titrant, oxidant, chromate and dichromate, organic synthesis, electroplating, preservatives, mordant, etc.
Safety
mouse oral LD o:190mg/kg. Chromium is a sensitizing source, and hexavalent chromium is irritant and corrosive. After inhalation may appear respiratory inflammation, asthma, chromium ulcers. It is strongly irritating to the skin. IARC carcinogenicity Review human carcinogenicity is well documented. This substance may be harmful to the environment, and special attention should be paid to the water body. Staff should be well protected, if accidentally touch the eyes, should immediately rinse with a large amount of flowing water. The working environment should have good ventilation conditions. Store in a cool, dry place, the container must be sealed to prevent moisture. Avoid co-storage and transportation with organic matter, flammable materials, reducing agents, oxides and acids.
Reference Information
| Overview | potassium dichromate (molecular formula K2Cr2O7) commonly known as potassium Carmine, decomposes to release oxygen at white heat temperature, has strong oxidation, it is a toxic and carcinogenic strong oxidizing agent, which is orange-red solid and plate-like crystal at room temperature. It is classified as a group I carcinogen by the International Agency for Research on Cancer (IARC) and may catch fire when exposed to combustibles. At 500 deg C above the oxidation of chromic acid and chromium oxide. Potassium dichromate solubility at low temperature is very small, and does not contain water of crystallization, easy to purify by overweight crystallization method; Also not easy to deliquescence, it is often used as a reference in the analysis. Because potassium dichromate has strong oxidizing properties under acidic conditions, it is commonly used in the laboratory to prepare chromic acid wash solution (a mixture of saturated potassium dichromate solution and concentrated sulfuric acid) to wash chemical glassware to remove reducing dirt from the walls of the vessel. After use, the lotion changes from dark red to green, and the lotion will be ineffective. Potassium dichromate is also used in analytical chemistry, commonly used for quantitative determination of reductive hydrogen sulfuric acid, sulfurous acid, ferrous ion and so on. In heating, potassium dichromate can also oxidize concentrated hydrochloric acid, the release of chlorine. Because the raw materials for the production of leather hydrolysate are mainly from the corner waste of the tannery, and these corner waste often contain potassium dichromate and sodium dichromate, in the production of hydrolyzed protein, potassium dichromate, sodium dichromate is naturally introduced into dairy products. After drinking can lead to joint osteoporosis, swelling and other poisoning problems. Repeated or long-term exposure to low concentrations of chromium compounds chromium plating workers, can occur chronic upper respiratory tract inflammation, chromium nasal disease, contact dermatitis, skin rash in the face, neck, hands, forearms and other exposed parts of the liver, kidney damage can also cause changes in the blood system. The incubation period for the occurrence of lung cancer is 10-20 years. Figure 1 is the molecular structure of potassium dichromate |
| solubility in water (g/100ml) | grams dissolved per 100ml of water at different temperatures (℃): 4.7g/0 ℃;7g/10 ℃;12.3g/20 ℃;18.1g/30 ℃;26.3g/40 ℃; 45.6g/60 ℃;73g/80 ℃ |
| Non-coagulated fixative | potassium dichromate was used as the fixative at a concentration of 1 to 3%. Its aqueous solution is slightly acidic, and it is also a strong oxidant. Therefore, it cannot be stored in advance with alcohol, formaldehyde solution, etc. At the same time, it is a strong hardening agent, and the penetration force is weak, so it is rarely used alone. Features: strong oxidant, strong hardener; Weak penetration. It is often used in combination with other fixatives. |
| toxicity | see sodium dichromate. |
| Use | used in the production of chrome alum, Chromium Oxide Green, chrome yellow pigment, electrode, printing ink, also used as tanning agent, enamel colorant, printing and Dyeing mordant used in the production of chrome alum, chrome oxide green, chrome yellow pigment. Enamel industry with its long powder, quartz sand and other mixed calcined enamel powder, as a green colorant. For the preparation of matches Medicine Head, from the role of oxidation and moisture. Used as a tanning agent for light leather. Mordant dyeing and printing are used as mordant. Synthetic fragrances were prepared for use as oxidants. Used for welding electrode, printing ink, metal passivation. Used as oxidants and catalysts in organic synthesis and raw materials for pharmaceuticals. used in the manufacture of chromium chemicals, mordant, ink, glass, perfume, pigment, ceramics, varnish, explosives, pharmaceuticals, etc. used as an oxidant, potassium chrome alum and reference for the preparation of chemical reagents calibration of sodium thiosulfate standard solutions. Drop analysis of chlorine, oxidants, Chromatography Reagents, organic synthesis. Liver function and gallbladder index were measured. Stool, etc. used as reference reagent, redox titrant, chromatography reagent and oxidant, also used in organic synthesis |
| production method | double decomposition method sodium dichromate (or the mother liquor after making sodium dichromate) is diluted and heated, A theoretical amount of potassium chloride (containing KCl>90%) was added for metathesis, the reaction temperature was 105-110 ° C., and the concentration of the reaction solution was controlled at 37-38 ° Bé to form a potassium dichromate solution. Add a small amount of sodium chlorate, adjust the pH value of the solution to 5~6 with sodium hydroxide, and then add a small amount of aluminum sulfate to flocculate the impurities. After clarification, remove the impurities, cool the solution to crystallize, and then centrifuge, wash, dry, prepared potassium dichromate finished product. The Na2Cr2O7 2KCl → K2Cr2O7 2NaC1 after separation of the mother liquor, sodium chloride crystals by concentration, while potassium dichromate is still soluble in the liquid phase. The sodium chloride is separated and washed with hot wash and hot water, which can be combined with the potassium dichromate mother liquor for evaporation. The mother liquor after sodium chloride separation is clarified to remove insolubles, the solution can be cooled to obtain sodium dichromate crystals again, and the secondary mother liquor can be returned to the reactor. |
| category | oxidant |
| toxicity grade | high toxicity |
| Acute toxicity | oral-mouse LD50: 190 mg/kg |
| explosive hazard characteristics | mixed with reductant, sulfur, phosphorus, etc, friction can burst |
| flammability hazard characteristics | toxic chromium and potassium oxide fumes from combustion |
| storage and transportation characteristics | The warehouse is ventilated and dried at low temperature; It is light and easy to discharge; It is combined with organic matter, reductant, sulfur and phosphorus combustible substances, separate storage of food raw materials |
| fire extinguishing agent | water and sand mist |
| Occupational Standard | TWA 0.05 mg (chromium)/m3 |
