Potassium chromate
Potassium chromate
CAS: 7789-00-6
Molecular Formula: CrK2O4
Potassium chromate - Names and Identifiers
| Name | Potassium chromate |
| Synonyms | Chromium(VI) Potassium chromate potassiumchromate6 dipotassiummonochromate neutralpotassiumchromate potassiumchromate[k2(cro4)] dipotassiumchromate(k2cro4) POTASSIUM CHROMATE ACS REAGENT dipotassium dioxido(dioxo)chromium Chromium(VI) Ion standard solution Fluka Chromium(VI) standard concentrate 10.00 g Cr(VI) Chromate ion chromatography standard solution Fluka CHROMIUM(VI) ATOMIC SPECTR. STD. CONC. 1 .00 G CR(VI), AMP. |
| CAS | 7789-00-6 |
| EINECS | 232-140-5 |
| InChI | InChI=1/Cr.2K.4O/q;2*+1;;;2*-1/rCrO4.2K/c2-1(3,4)5;;/q-2;2*+1 |
| InChIKey | XMXNVYPJWBTAHN-UHFFFAOYSA-N |
Potassium chromate - Physico-chemical Properties
| Molecular Formula | CrK2O4 |
| Molar Mass | 194.1903 |
| Density | 1.00g/mLat 20°C |
| Melting Point | 971 °C (lit.) |
| Water Solubility | 640 g/L (20 ºC) |
| Solubility | H2O: soluble |
| Vapor Density | 6.7 (vs air) |
| Appearance | Solid |
| Specific Gravity | 2.732 |
| Color | Yellow |
| 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 | 14,7622 |
| PH | 9.0-9.8 (50g/l, H2O, 20℃) |
| Storage Condition | Store below +30°C. |
| Stability | Stable. Strong oxidizing agent - contact with combustible materials may lead to fire or violent reaction. Incompatible with strong reducing agents, combustible materials. |
| Physical and Chemical Properties | Characteristics of lemon yellow crystal. melting point 968.3 ℃ relative density 2.732 solubility soluble in water, insoluble in alcohol. |
| Use | Mainly used in the manufacture of chemical reagents and pigments |
Potassium chromate - Risk and Safety
| Risk Codes | R49 - May cause cancer by inhalation R46 - May cause heritable genetic damage R43 - May cause sensitization by skin contact R51/53 - Toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment. R8 - Contact with combustible material may cause fire R50/53 - Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment. R36/37/38 - Irritating to eyes, respiratory system and skin. R22 - Harmful if swallowed R45 - May cause cancer R52/53 - Harmful to aquatic organisms, may cause long-term adverse effects in the aquatic environment. R25 - Toxic if swallowed R42/43 - May cause sensitization by inhalation and skin contact. R20 - Harmful by inhalation |
| 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. S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S23 - Do not breathe vapour. |
| UN IDs | UN 3288 6.1/PG 3 |
| WGK Germany | 3 |
| RTECS | GB2940000 |
| TSCA | Yes |
| HS Code | 28415000 |
| Hazard Class | 5.1 |
| Packing Group | III |
Potassium chromate - Upstream Downstream Industry
| Raw Materials | Potassium hydroxide Potassium dichromate |
Potassium chromate - Nature
Open Data Verified Data
lemon-yellow monoclinic crystals. Melting point 975 C; d 2. 73. Soluble in 1.6 cold water, 1.2 boiling water, the solution of phenolphthalein, litmus alkaline, insoluble in ethanol. Strong oxidant. Exposure to organic matter may cause combustion risk. By high heat decomposition, release of toxic smoke.
Last Update：2024-01-02 23:10:35
Potassium chromate - Preparation Method
Open Data Verified Data
Industrial potassium dichromate was dissolved in hot water and potassium bicarbonate was added. The solution is neutralized with reagent potassium hydroxide, filtered and evaporated until crystallization occurs, and then cooled and suction-filtered to crystallize.
Last Update：2022-01-01 09:02:38
Potassium chromate - Use
Open Data Verified Data
The reagent was analyzed, and barium and silver were microanalyzed. It is also used for the determination of the content of pesticide DDT and sodium pentoxide, as well as as oxidizing agent, mordant, metal rust inhibitor and so on.
Last Update：2022-01-01 09:02:38
Potassium chromate - Safety
Open Data Verified Data
rabbit intramuscular injection of LDso: 11 mg/kg. It is corrosive to eyes, skin and mucous membranes and can cause severe burns. 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, ventilated warehouse. Keep away from fire and heat source. Keep the container sealed. Should be stored separately from the reducing agent, combustible, combustible, etc. It cannot be stored and mixed with food, feed, etc.
Last Update：2022-01-01 09:02:39
Potassium chromate - Reference Information
| EPA chemical substance information | information provided by: ofmpeb.epa.gov (external link) |
| inorganic compound | the common name of potassium chromate is chromonite, which is an inorganic compound and is a yellow orthogonal or hexagonal crystal at room temperature. The relative density is 2.732, the melting point is 968 deg C, toxic. Soluble in water, soluble chromate ion hydrolysis solution is alkaline, insoluble in alcohol and ether. The acid is added to the yellow potassium chromate solution and the solution turns orange, which is the color of the dichromate radical. The mutual transformation between chromate and dichromate in solution has the following equilibrium: when adding acid to potassium chromate solution, the equilibrium moves in the direction of forming potassium dichromate, when alkali is added to the potassium dichromate solution, the equilibrium is shifted in the direction in which potassium chromate is produced. Potassium chromate is oxidative, and its reaction with the reducing agent itself is reduced to the tetrahydroxychromium (III) ion Cr(OH)-4 (I. E., chromate ion CrO-2) in an alkaline medium. Adding solutions containing barium ions, lead ions and silver ions to the potassium chromate solution, respectively, can generate the corresponding insoluble chromates: barium chromate acro4 (yellow), lead chromate pbCrO4 (yellow), silver chromate Ag2CrO4 (brick red). The presence of chromate ions can be demonstrated by the characteristic color of these poorly soluble chromates. Potassium chromate can be used as analysis reagent, oxidant, mordant, metal rust inhibitor, barium, silver trace analysis, can also be used for tanning, medicine and other aspects of the raw materials of chromium compounds. Using chromite Fe(CrO2)2 powder as raw material, calcined with potassium hydroxide and limestone (dolomite) in air, and then extracted with potassium sulfate solution, potassium chromate can be prepared. |
| potassium chromate indicator method | with potassium chromate (K2CrO4) as indicator, silver nitrate (AgNO3) as a standard solution of precipitation titration (Silver method), also known as Mohr (Mohr), mainly for the determination of chloride (Cl-) or bromide (Br-). In the assay, a small amount of K2CrO4 was added as an indicator and titrated with AgNO3 standard solution. After the start of titration, the first precipitation of white (silver chloride) or light yellow (silver bromide), when Cl-or Br-quantitative precipitation, A very small excess of the silver nitrate solution causes a sudden increase in the concentration of silver ions (Ag +) in the solution, while a brick red silver chromate (Ag2CrO4) precipitate is immediately generated, indicating the end point of the titration. The amount of indicator and the acidity of the solution are the two main problems in this titration. When the concentration of K2CrO4 is too high, the color of the titrated solution is too deep, which hinders the observation of the color of Ag2CrO4 precipitate at the end point; When the concentration of K2CrO4 is too low, the silver halide is quantitatively precipitated, A considerable excess of silver nitrate solution must also be added dropwise before a silver chromate precipitate is generated to indicate the end point of the titration, thereby increasing the titration error. When 0.1mol/1 halide is titrated with 0.1mol/1 AgNO3 solution and K2CrO4 is added at a concentration of 5 × 10-3mol/l, the endpoint error of only + 0.06% can be considered to not affect the accuracy of the analysis results. K2CrO4 indicator method can not be carried out in acidic or strong alkaline solution, because the pH value of K2CrO4 is changed to potassium dichromate (K2Cr2O7), and when the pH is too high, Ag + will be precipitated in the form of silver oxide (Ag2O), A suitable range of acidity is pH = 6.5-10.5. If ammonium salt is present in the solution, pH = 6.5-7.2 is preferred. The potassium chromate indicator method can only be used to directly titrate Cl-or Br-ions. When the two ions coexist, the total amount of them is titrated. Or thiocyanate ions (SCN-), because they are easily adsorbed by precipitation and the end point is unclear. This method is not suitable for using Cl-titration of Ag +, to determine Ag + can be used back titration, that is, in the solution to add a certain amount of excess NaCl standard solution, the excess of Cl-ions was then titrated with AgNO3 standard solution. Any of the cations in the solution that can precipitate with CrO2-4 or the anions that precipitate with Ag + will interfere with the determination. The potassium chromate indicator method is mainly used for the determination of Cl-in extremely dilute solutions, such as the determination of Cl-in drinking water and impurities in industrial products. Figure 1 potassium chromate indicator |
| potassium dichromate | potassium dichromate is also known as potassium Carmine. It is an orange-red Triclinic or needle-like crystal. Density 2.676g/cm3. Melting point 398 °c. Melt in water, insoluble in ethanol. Strong oxidation. Decomposition at 1300 °c. potassium dichromate is commonly used in the production of chromium, and the porcelain glaze in the melt coloring. It is colored titanium milk yellow glaze and titanium yellow glaze colorant, its dosage is generally 0.06% ~ 0.12%. Potassium dichromate and copper oxide can also be prepared with green, bamboo, Green and other colored glaze. However, these colored glazes generally have a poor gloss due to the effect of chromate. The color glaze made of chromium oxide or potassium dichromate (sodium) often presents yellow-green color due to the change of valence state of chromium ion in the melting process. Potassium dichromate is also commonly used to make a variety of green and pink pigments. potassium dichromate shall meet the specified indicators: potassium dichromate content ≥ 99%, chloride (calculated as Cl) content ≤ 0.08%, and water-insoluble matter ≤ 0.05%. |
| solubility in water (g/100ml) | grams dissolved per 100ml of water at different temperatures (℃): 56.3g/0 ℃;60g/10 ℃;63.7g/20 ℃;66.7g/30 ℃;67.8g/40 ℃; 70.1g/60 ℃;74.5g/90 ℃ |
| toxicity | see sodium chromate. |
| Use | use as analytical reagent, oxidant, mordant and metal rust inhibitor for the manufacture of chromate. Used as oxidant, mordant for printing and dyeing. Used for ink, pigment, enamel, metal corrosion, etc. mainly used in the manufacture of chemical reagents and pigments, etc. drop analysis for the determination of barium, silver, etc., determination of pesticide DDT and pentachlorophenol sodium content. |
| production method | neutralization method potassium dichromate was dissolved in mother liquor and water and added to the reactor, potassium hydroxide is added under stirring to carry out neutralization reaction, and potassium chromate is weakly alkaline, which is concentrated by evaporation, cooled crystallization, solid-liquid separation and drying to obtain potassium chromate finished product. The mother liquor separated from K2Cr2O7 2KOH → 2K2CrO4 H2O was returned to the dissolution step for dissolving potassium dichromate. |
| toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |
Last Update：2024-04-10 22:29:15
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View History
Potassium chromate
2-AMINO-4-CHLORO-6-NITROPHENOL
5-Bromopentan-1-ol
Cyclopropa[4,5]cyclopenta[1,2-b]pyridine (9CI)
2-(1H-IMIDAZOL-4-YL)ACETIC ACID HYDROCHLORIDE
cromoglicic acid
Hexa-n-butyldizinn
Ammonium nitrite
2-AMINO-4-CHLORO-6-NITROPHENOL
5-Bromopentan-1-ol
Cyclopropa[4,5]cyclopenta[1,2-b]pyridine (9CI)
2-(1H-IMIDAZOL-4-YL)ACETIC ACID HYDROCHLORIDE
cromoglicic acid
Hexa-n-butyldizinn
Ammonium nitrite
Raw Materials for Potassium chromate