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Potassium chromate

Inorganic compound Potassium chromate indicator method Potassium dichromate Solubility in water (g/100ml) Toxicity Chemical properties Application Preparation
Potassium chromate
Potassium chromate
Chemical Name:
Potassium chromate
CHROMATE;BETZ 0213;tarapacaite;Chromium(VI);Chromate, CrO;chromateofpotash;chromateofpotass;CHROMATE STANDARD;potassiumchromate6;CHROMATE INDICATOR
Molecular Formula:
Formula Weight:
MOL File:

Potassium chromate Properties

Melting point:
971 °C(lit.)
1.00 g/mL at 20 °C
vapor density 
6.7 (vs air)
storage temp. 
H2O: soluble
9.0-9.8 (50g/l, H2O, 20℃)
Water Solubility 
640 g/L (20 ºC)
Stable. Strong oxidizing agent - contact with combustible materials may lead to fire or violent reaction. Incompatible with strong reducing agents, combustible materials.
CAS DataBase Reference
7789-00-6(CAS DataBase Reference)
EPA Substance Registry System
Chromic acid (H2CrO4), dipotassium salt(7789-00-6)
  • Risk and Safety Statements
  • Hazard and Precautionary Statements (GHS)
Hazard Codes  T,N,O
Risk Statements  49-46-43-51/53-8-50/53-36/37/38-22-45-52/53-25-42/43-20
Safety Statements  53-45-60-61-36/37-26-23
RIDADR  UN 3288 6.1/PG 3
WGK Germany  3
RTECS  GB2940000
HazardClass  5.1
PackingGroup  III
Hazardous Substances Data 7789-00-6(Hazardous Substances Data)
Signal word: Danger
Hazard statements:
Code Hazard statements Hazard class Category Signal word Pictogram P-Codes
H301 Toxic if swalloed Acute toxicity,oral Category 3 Danger P264, P270, P301+P310, P321, P330,P405, P501
H315 Causes skin irritation Skin corrosion/irritation Category 2 Warning P264, P280, P302+P352, P321,P332+P313, P362
H317 May cause an allergic skin reaction Sensitisation, Skin Category 1 Warning P261, P272, P280, P302+P352,P333+P313, P321, P363, P501
H319 Causes serious eye irritation Serious eye damage/eye irritation Category 2A Warning P264, P280, P305+P351+P338,P337+P313P
H335 May cause respiratory irritation Specific target organ toxicity, single exposure;Respiratory tract irritation Category 3 Warning
H340 May cause genetic defects Germ cell mutagenicity Category 1A, 1B Danger
H350 May cause cancer Carcinogenicity Category 1A, 1B Danger
H400 Very toxic to aquatic life Hazardous to the aquatic environment, acute hazard Category 1 Warning P273, P391, P501
H410 Very toxic to aquatic life with long lasting effects Hazardous to the aquatic environment, long-term hazard Category 1 Warning P273, P391, P501
Precautionary statements:
P201 Obtain special instructions before use.
P261 Avoid breathing dust/fume/gas/mist/vapours/spray.
P273 Avoid release to the environment.
P280 Wear protective gloves/protective clothing/eye protection/face protection.
P391 Collect spillage. Hazardous to the aquatic environment
P305+P351+P338 IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continuerinsing.
P308+P313 IF exposed or concerned: Get medical advice/attention.
P333+P313 IF SKIN irritation or rash occurs: Get medical advice/attention.
P405 Store locked up.

Potassium chromate price More Price(12)

Manufacturer Product number Product description CAS number Packaging Price Updated Buy
Sigma-Aldrich 02673 Chromium(VI) atomic spectroscopy standard concentrate 1.00 g Cr(VI) 1.00 g/L, for 1L standard solution, analytical standard 7789-00-6 1ea $24.8 2017-11-08 Buy
Sigma-Aldrich 1.04952 Potassium chromate 7789-00-6 1EA $133 2017-11-08 Buy
Alfa Aesar 12610 Potassium chromate, ACS, 99.0% min 7789-00-6 100g $37.1 2017-11-08 Buy
Alfa Aesar 12610 Potassium chromate, ACS, 99.0% min 7789-00-6 500g $124 2017-11-08 Buy
Sigma-Aldrich 12249 Potassium chromate puriss., ≥99% 7789-00-6 100g $45.9 2017-11-08 Buy

Potassium chromate Chemical Properties,Uses,Production

Inorganic compound

Potassium chromate, commonly known as tarapacaite, is an inorganic compound, which is yellow orthorhombic or hexagonal crystal at room temperature. The relative density is 2.732, and the melting point is 968 °C. It is toxic and can disolve in water to form alkaline chromate ion hydrolysis solution. And it is insoluble in alcohol and ether. After added acid, the yellow solution of potassium chromate will turn orange, which is the color of dichromate. There is an equilibrium between the conversion of chromate and dichromate in the solution:
When the acid is added to the potassium chromate solution, the equilibrium will shift toward the direction of generating potassium dichromate, and when the alkali is added to the potassium dichromate solution, the equilibrium will shift to the direction of generating potassium chromate. Potassium chromate has oxidative properties, and it can react with the reducing agent in alkaline medium to form Cr(OH)4-(namely CrO¬2-). Adding different solutions respectively containing barium ion, lead ion and silver ion to the potassium chromate solution will form the corresponding insoluble chromate: barium chromate BaCrO4 (yellow), lead chromate pbCrO4 (yellow), silver chromate Ag2CrO4(Brick red). And the presence of chromate ions can be demonstrated by the characteristic color of these insoluble chromates. Potassium chromate can be used as analytical reagent, oxidant, mordant, metal rust inhibitor, and used for barium and silver trace analysis. It can also be used as raw materials of tanning and medicine industry and other chromium compounds. Chromite Fe(CrO2)2 powder can be used as raw material and calcined with potassium hydroxide, limestone (dolomite) in the air, and then extracted with potassium sulfate solution to obtain potassium chromate.
The above information is edited by Xiao Nan of Chemicalbook.

Potassium chromate indicator method

Potassium chromate indicator method, also known as Moore (Mohr), is a precipitation titration method (silver method) that uses potassium chromate (K2CrO4) as indicator and silver nitrate (AgNO3) as the standard solution. This method is mainly used for the determination of chlorine Ion (Cl-) or bromide ion (Br-). Add a small amount of K2CrO4 as indicator before stating determination, and then titrate with AgNO3 standard solution. After the start of the titration, the precipitate of white (silver chloride) or pale yellow (silver bromide) precipitates first. When Cl-or Br-precipitates quantitatively, a little excess silver nitrate solution will cause the concentration of Ag+ suddenly increasing to immediately generate brick red silver chromate (Ag2CrO4) precipitation, indicating the titration endpoint. The amount of indicator and the acidity of the solution are two major problems of this titration method. If the K2CrO4 concentration is too high, the color of the titration solution will be too deep to hinder the observation of Ag2CrO4 precipitation color in the end; if the K2CrO4 concentration is too low, an excessively considerable amount of silver nitrate solution will be needed after the quantitative precipitation of silver halide to generate silver chromate precipitation to instruct the titration end point, which will results the titration error increasing. When the 0.1mol/l AgNO3 solution is used to titrate the 0.1mol/l halide, if the concentration of K2CrO4 is 5× 10-3mol/l, the end point error is only +0.06%, which can be thought that the accuracy of the analysis result is not affected. K2CrO4 indicator method can not be carried out in acidic or alkaline solution, because K2CrO4 will be converted to potassium dichromate (K2Cr2O7) at a small pH value, and Ag+ will precipitate in the form of silver oxide (Ag2O) when the pH is too high. Commonly, the suitable acidity range is pH = 6.5~ 10.5, but when there are ammonium salts in solution, the solution acidity pH = 6.5~7.2 is appropriate.
The potassium chromate indicator method can only be used for the direct titration of Cl-or Br-ions, and the titration result is their total when coexisting. This method is not suitable for the determination of iodide ion (I-) or thiocyanate ion (SCN-), because they are too easily absorbed by sedimentation and the end point is unclear. This method is also not suitable for titrating Ag+ with Cl-, but Ag+ can be determined using the back titration, namely add an excessive amount of NaCl standard solution in the test solution, and then use AgNO3 standard solution to titrate excess Cl-ions. In the solution, all the cations that can form precipitates with CrO2-4 or the anions that can precipitate with Ag+ will interfere with the determination. Potassium chromate indicator method is mainly used for the determination of the Cl-ions in very dilute solution, such as the determination of Cl-in drinking water and industrial products impurities.

Potassium dichromate

Potassium dichromate, also known as red alum potassium, is orange-red triclinic crystal or needle-like crystal. The density is 2.676 g/cm3. The melting temperature is 398 °C. It is soluble in water and insoluble in ethanol. It has strong oxidizing property and decomposes at 1300 °C.
In production, potassium dichromate is always used to introduce chromium to make the enamel colored when melting. It is the coloring agent of colored titanium milk yellow glaze and titanium yellow glaze, and the used dosage is generally 0.06%~0.12%. Potassium dichromate and copper oxide can also be mix-used to obtain green, bamboo green, fruit green and other color glaze. However, these colored glazes are generally less glossy due to the influence of chromate.
The color glaze obtained from chromium oxide or potassium (sodium) dichromate often is yellow-green due to the valence change of chromium ions in the melting process. Potassium dichromate is also commonly used to make various green pigments and pink pigments.
Potassium dichromate should meet the required targets: potassium dichromate content ≥ 99%, chloride (Cl) content ≤ 0.08%, water insoluble ≤ 0.05%.
The above information is compiled by Yaoyao of Chemicalbook.

Solubility in water (g/100ml)

Dissolved grams per 100 ml of water at different temperatures (°C):
60 g/10 °C; 63.7 g/20 °C; 66.7 g/30 °C; 67.8 g/40 °C
70.1 g/60 °C; 74.5 g/90 °C


See sodium chromate

Chemical properties

Lemon yellow orthorhombic crystal; Soluble in water; insoluble in alcohol


Used as analytical reagent, oxidant, mordant and metal rust inhibitor;used for the manufacture of chromate,used as oxidant and mordant of printing and dyeing. Used for ink, paint, enamel, metal corrosion and so on,mainly used in the manufacture of chemical reagents and pigments.


Neutralization method: Dissolve potassium dichromate in the mother liquor and water, and then add the mixture to the reactor. Next add potassium hydroxide under stirring to carry out neutralization reaction. The produced potassium chromate is weakly alkaline, and then evaporated for concentration, cooled for crystallization, separated and dried to obtain the finished potassium chromate products.
K2Cr2O7 + 2KOH → 2K2CrO4 + H2O
The separated mother liquor will be returned to the dissolving step for dissolving potassium dichromate.

Chemical Properties

lemon-yellow crystals


It is used as an oxidizing agent.


Has a limited application in enamels, finishing leather, rustproofing of metals, being replaced by the sodium salt; as reagent in analytical chemistry.


ChEBI: A potassium salt consisting of potassium and chromate ions in a 2:1 ratio.

General Description

Potassium chromate is a yellow crystalline solid. Potassium chromate is soluble in water. The primary hazard is the threat to the environment. Immediate steps should be taken to limit its spread to the environment. Potassium chromate is used in chemical analysis, in making pigments for paints and inks, as a fungicide, and to make other chromium compounds.

Air & Water Reactions

Soluble in water.

Reactivity Profile

Oxidizing agents, such as Potassium chromate , can react with reducing agents to generate heat and products that may be gaseous (causing pressurization of closed containers). The products may themselves be capable of further reactions (such as combustion in the air). The chemical reduction of materials in this group can be rapid or even explosive, but often requires initiation (heat, spark, catalyst, addition of a solvent). Explosive mixtures of inorganic oxidizing agents with reducing agents often persist unchanged for long periods if initiation is prevented. Such systems are typically mixtures of solids, but may involve any combination of physical states. Some inorganic oxidizing agents are salts of metals that are soluble in water; dissolution dilutes but does not nullify the oxidizing power of such materials. Organic compounds, in general, have some reducing power and can in principle react with compounds in this class. Actual reactivity varies greatly with the identity of the organic compound. Inorganic oxidizing agents can react violently with active metals, cyanides, esters, and thiocyanates.

Health Hazard

Inhalation causes local irritation of mucous membranes; continuing nose irritation can result in perforation of nasal septum. Ingestion may cause violent gastroenteritis, circulatory collapse, vertigo, coma, and toxic nephritis; ingestion of excessive quantities can be fatal. Contact with eyes causes severe irritation and conjunctivitis. Repeated or prolonged exposure to dust, mist, or solutions may cause dermatitis; contact with breaks in the skin may cause ``chrome sores'' appearing as slow-healing, hard-rimmed ulcers which leave the area vulnerable to infection.

Fire Hazard

Behavior in Fire: May increase intensity of fire if in contact with combustible materials. Cool containers and spilled material with plenty of water.

Purification Methods

Crystallise it from conductivity water (0.6g/mL at 20o), and dry it between 135o and 170o.

Potassium chromate Preparation Products And Raw materials

Raw materials

Preparation Products

Potassium chromate Suppliers

Global( 159)Suppliers
Supplier Tel Fax Email Country ProdList Advantage
Mainchem Co., Ltd.
+86-0592-6210733 CHINA 32765 55
Sinopharm Chemical Reagent Co,Ltd. 86-21-63210123
86-21-63290778 86-21-63218885 China 9975 79
J & K SCIENTIFIC LTD. 400-666-7788 +86-10-82848833
+86-10-82849933; China 96815 76
Meryer (Shanghai) Chemical Technology Co., Ltd. +86-(0)21-61259100(Shanghai) +86-(0)755-86170099(ShenZhen) +86-(0)10-62670440(Beijing)
+86-(0)21-61259102(Shanghai) +86-(0)755-86170066(ShenZhen) +86-(0)10-88580358(Beijing) China 40399 62
Alfa Aesar 400-610-6006; 021-67582000
021-67582001/03/05 China 30308 84
Energy Chemical 021-58432009 / 400-005-6266
021-58436166-800 China 44192 61
Adamas Reagent, Ltd. 400-600-9262 China 14017 59
Shanghai Hanhong Scientific Co.,Ltd. 021-54306202,021-54308259
+86-21-54291107 China 31110 64
Chengdu XiYa Chemical Technology Co., Ltd. 4008-626-111
028-84752058 China 9740 57
Tianjin heowns Biochemical Technology Co., Ltd. 400 638 7771 China 14543 57

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