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Potassium Dichromate is an inorganic chromium(VI) salt with the formula K₂Cr₂O₇ and a molecular weight of 294.18 g/mol, identified by the registry entries CAS No 7778-50-9 and EC No 231-906-6. It occurs as orange-red crystals, is odorless, soluble in water and not hygroscopic. It is a strong oxidizer; its aqueous solution is acidic. Commercially it is offered in analytical reagent, primary standard and technical grades.
Also known as potassium bichromate, this salt acts as an oxidizer by accepting electrons when hexavalent chromium is reduced to trivalent chromium in acidic media; the orange solution turns green in the process. This property is used in titrations, in the determination of chemical oxygen demand and in organic oxidation reactions. In dry crystalline form it is stable and melts at about 398 °C.
Also searched under the name Potassium Dichromate, this product has been used in laboratory work, leather, pigments, printing and metal surface treatment. Because it contains hexavalent chromium, it is carcinogenic and toxic; the intended use and the regulatory status must be evaluated together. This product can be supplied from ATAMAN KİMYA; for product selection, technical information and supply requests, contacting ATAMAN KİMYA is recommended.
WHAT IS POTASSIUM DICHROMATE?
Potassium Dichromate is an inorganic compound that is the potassium salt of dichromic acid and contains hexavalent chromium. Its orange-red crystals are soluble in water and insoluble in ethanol and acetone. Because of its strong oxidizing nature, it has long been used in laboratories and in industry.
The substance occurs in nature as a very rare mineral called lópezite. The commercial product, however, is not obtained from natural sources but is produced synthetically.
Production begins with roasting chromite, the chromium ore, in air with an alkali carbonate or hydroxide. The resulting chromate is acidified and converted into sodium dichromate. When sodium dichromate is reacted with potassium chloride, the less soluble potassium dichromate crystallizes and separates.
Sodium dichromate is produced worldwide in much larger quantities and has replaced the potassium salt in many industrial uses. Potassium dichromate, thanks to its non-hygroscopic nature, is preferred particularly in laboratories and in sensitive applications.
Containing hexavalent chromium, Potassium Dichromate is one of the most closely monitored chemicals. The International Agency for Research on Cancer (IARC) classifies chromium(VI) compounds as carcinogenic to humans, that is, Group 1. In Europe the substance falls under the substances of very high concern and authorization list.
For this reason, the product should be used only by trained personnel, where suitable engineering controls and personal protective equipment are in place, and in compliance with the relevant legislation. Where possible, less hazardous alternatives should be evaluated.
COMMON PRODUCT AND CHEMICAL NAMES OF POTASSIUM DICHROMATE:
Potasyum Dikromat
Potassium Dichromate
Potasyum bikromat
Potassium Bichromate
Dipotasyum dikromat
Dipotassium dichromate
Dipotassium bichromate
Potasyum dikromat(VI)
Potassium dichromate(VI)
Dipotassium salt of dichromic acid
Dichromic acid, dipotassium salt
Potassium dichromate ACS
Potassium dichromate reagent grade
Potassium dichromate AR
Potassium dichromate technical grade
Potassium dichromate primary standard
Kaliumdichromat
Kaliumbichromat
Dichromate de potassium
Bichromate de potassium
Dicromato de potasio
Bicromato de potasio
Dicromato di potassio
Lópezite (natural mineral form)
K₂Cr₂O₇
Most of these names refer to the same substance in terms of different spellings, languages or grades. Dichromate and bichromate denote the same anion; bichromate is an old and commercial usage, and dichromate is preferred in current nomenclature.
Potassium Dichromate and Kaliumdichromat are the English and German names; Dichromate de potassium, Dicromato de potasio and Dicromato di potassio are the French, Spanish and Italian equivalents.
The terms ACS, AR, reagent grade and primary standard indicate the quality grade, not the chemical identity. Primary standard describes a high-purity grade that can be weighed directly to prepare titration solutions.
The similarity in product names can be misleading. Potassium chromate (K₂CrO₄, CAS No 7789-00-6) is yellow and is a separate substance. Sodium dichromate (CAS No 7789-12-0), ammonium dichromate (CAS No 7789-09-5) and chromium trioxide (CAS No 1333-82-0) also have different registrations and properties.
Potassium chrome alum, on the other hand, is a salt of trivalent chromium and should not be confused with Potassium Dichromate. In purchase requests, the CAS number should be stated in addition to the product name.
Products sold as a solution contain the same substance as the solid product but may have separate classification and transport rules. If a solution is required, the concentration and solvent medium should be specified separately.
CAS NO, EC / EINECS NO AND CHEMICAL IDENTIFICATION OF POTASSIUM DICHROMATE
Product name: Potassium Dichromate / Potasyum Dikromat
Chemical name: Dipotassium dichromate; dipotassium salt of dichromic acid
CAS No: 7778-50-9
EC / EINECS No: 231-906-6
Molecular formula: K₂Cr₂O₇
Molecular weight: 294.18 g/mol
Chemical class: Inorganic dichromate salt; hexavalent chromium (chromium(VI)) compound
Main functions: Oxidizing agent, standard in redox titrations, oxidizing reagent in chemical oxygen demand determination, spectrophotometer calibration standard, chromium(VI) source, intermediate for chromium(III) salts
In the classification and labeling record of the European Union, the index number is 024-002-00-6. The customs tariff position is mostly under 2841.50.
When giving identification data, the form of the product should be taken into account. The number 7778-50-9 is used for solid Potassium Dichromate; solutions and mixtures may be classified separately.
The CAS number is necessary to match the product to the correct substance; however, on its own it does not show that the product is suitable for a specific application or compliant with legislation.
Potassium Dichromate is not a food additive and is not used as a cosmetic ingredient. For this reason, no food additive number or INCI name is given for this substance.
CHEMICAL STRUCTURE AND MOLECULAR PROPERTIES OF POTASSIUM DICHROMATE
Potassium Dichromate is an ionic salt formed by two potassium cations (K⁺) and the dichromate anion (Cr₂O₇²⁻). In the solid state these ions are held together in the crystal lattice; when dissolved in water it dissociates into K⁺ and dichromate ions.
The dichromate anion consists of two tetrahedral CrO₄ units sharing one oxygen atom. The structure resembles the pyrophosphate ion: on either side of the Cr–O–Cr bridge, each chromium atom carries three terminal oxygen atoms.
Each chromium atom is in the +6 oxidation state. This is the highest valence of chromium, and its d orbitals contain no electrons. This electron deficiency explains chromium’s tendency to accept electrons, that is, its oxidizing power.
The Cr–O bonds have covalent character, and the negative charge is distributed over the anion. The bond between potassium and dichromate, on the other hand, is ionic. For this reason the substance is an ionic crystal and dissociates readily into ions in water.
The dichromate ion has a pH-dependent equilibrium in aqueous media: Cr₂O₇²⁻ + H₂O ⇌ 2 HCrO₄⁻ ⇌ 2 CrO₄²⁻ + 2 H⁺. In acidic media orange dichromate predominates, and in basic media yellow chromate predominates. When alkali is added to the solution, the color turns from orange to yellow.
In terms of polarity, the substance is ionic and hydrophilic; it does not dissolve in organic solvents. Its aqueous solution reacts acidically because of the hydrogen chromate equilibrium. For this reason the pH of the solution is in the range of about 3.5–4, depending on concentration.
The most important property is its redox character. In acidic media dichromate accepts six electrons and is reduced to two Cr³⁺ ions: Cr₂O₇²⁻ + 14 H⁺ + 6 e⁻ → 2 Cr³⁺ + 7 H₂O. The standard reduction potential is about +1.33 V.
This potential makes dichromate more selective than permanganate, yet strong enough to oxidize many organic and inorganic substances. Cr(VI) is orange and Cr(III) is green; this color change is used as a visual indicator of the reaction.
Solid Potassium Dichromate is stable at room temperature. Above about 500 °C it decomposes, releasing oxygen; the products include potassium chromate and chromium(III) oxide.
With concentrated sulfuric acid in the cold, species such as chromium trioxide (chromic anhydride) can form, and with hydrochloric acid, species such as chromyl chloride. For this reason, mixing with acids should be carried out only under controlled conditions and by expert personnel.
The structural factors affecting participation in reactions can be summarized under three headings. The first is the high oxidation state of chromium and the oxygen-rich structure. The second is the pH-dependent dichromate–chromate equilibrium. The third is the presence of reducing agents and acids in the medium.
PHYSICAL AND CHEMICAL PROPERTIES OF POTASSIUM DICHROMATE
General technical specifications:
Values may vary depending on the manufacturer, grade and measurement method; the information below is for general informational purposes and does not replace manufacturer-specific TDS and SDS documents.
Physical appearance: Orange-red, odorless crystals or crystalline powder
Chemical character: Strong oxidizer; hexavalent chromium salt; aqueous solution acidic
Molecular formula: K₂Cr₂O₇
Molecular weight: 294.18 g/mol
CAS No: 7778-50-9
EC / EINECS No: 231-906-6
Purity (assay): In analytical reagent grades generally at least 99.9 percent; in ACS reagent grade at least 99 percent; in some technical grades at least 99.7 percent is given. These are specification limits that depend on grade and manufacturer. In the grade certified as a primary standard by national metrology institutes, purity reaches about 99.99 percent
Density: Approx. 2.68 g/cm³ for the solid (20 °C)
Bulk density: Varies with grade and form; given as approx. 1250 kg/m³ in some analytical grades
Solubility in water: Reported in most documents as approx. 115–125 g/L at 20 °C and increases markedly with temperature. In some safety data sheets a much lower value such as 29.4 g/L is also seen. Insoluble in ethanol and acetone
pH (aqueous solution): Depends on concentration; reported as 3.5–5.0 for an approx. 29 g/L solution and approx. 3.6 for a 100 g/L solution
Decomposition: Melts at approx. 398 °C; above approx. 500 °C it decomposes, releasing oxygen
Moisture: Not hygroscopic; in analytical grades loss on drying is generally at most 0.05 percent
Iron (Fe) content: In analytical grades generally at most 0.001 percent
Heavy metals (Pb, Cu, etc.): In analytical grades at most 0.005 percent for lead and at most 0.001 percent for copper are given; in technical grades the limits depend on the manufacturer
Chloride content: In analytical grades at most 0.001 percent; in some technical-grade specifications approx. 0.07 percent
Reactivity: A strong oxidizer; may react violently with reducing agents, organic and combustible materials. It is reported to react explosively with hydrazine and hydroxylamine. On contact with acids, chromium trioxide or toxic gas species may form
Short Description of Physical Properties
Potassium Dichromate is stable in dry, closed packaging. However, some physical constants given in data sheets may seem contradictory at first glance. Most of these differences arise from measurement conditions or differences in definitions in the documents.
For solubility, most documents give a value of approx. 115–125 g/L at 20 °C; the international chemical safety card reports 12 g in 100 mL of water. In some SDSs, a much lower value such as 29.4 g/L appears.
For this reason, temperature and measurement conditions should be checked when obtaining solubility information. In critical calculations, the manufacturer’s own document should be taken as the basis.
The melting point is given as approx. 398 °C. Although some documents state 500 °C as the boiling point, the substance does not boil at this temperature; it decomposes.
The pH of the aqueous solution depends on concentration. It is 3.5–5.0 in an approx. 29 g/L solution and approx. 3.6 in a 100 g/L solution. For this reason, pH should not be given as a single value without stating the measurement conditions.
Density and bulk density are separate properties. The density of the solid is approx. 2.68 g/cm³. Bulk density is lower because it also includes the voids between particles.
Heavy metal, iron and chloride values are not fixed properties inherent to the substance but quality parameters that depend on production and purification quality. These values should always be checked against the manufacturer’s TDS and COA documents.
HOW DOES POTASSIUM DICHROMATE WORK AT THE MOLECULAR LEVEL?
The basic action of Potassium Dichromate is the reduction of hexavalent chromium to trivalent chromium in acidic media. The required protons are supplied by the medium: Cr₂O₇²⁻ + 14 H⁺ + 6 e⁻ → 2 Cr³⁺ + 7 H₂O. For this reason the oxidizing power increases with acid concentration.
Dichromate takes these electrons from the reducing agent in the medium. For iron(II) the reaction is Cr₂O₇²⁻ + 6 Fe²⁺ + 14 H⁺ → 2 Cr³⁺ + 6 Fe³⁺ + 7 H₂O. It is a fast reaction with known stoichiometry.
For this reason it is used in titrimetric analysis. The end point is determined with redox indicators such as diphenylamine sulfonate or ferroin.
The fact that the substance can be crystallized in high purity, is not hygroscopic and gives solutions that remain stable for a long time makes it useful as a primary standard.
In the determination of chemical oxygen demand (COD), the oxidizable organic matter in the sample is oxidized by excess dichromate in strong sulfuric acid medium at high temperature. While organic carbon is converted to carbon dioxide, Cr(VI) is reduced to Cr(III).
The amount of dichromate consumed gives the COD value as an oxygen equivalent. Mercury(II) sulfate is used to prevent chloride interference, and silver sulfate as a catalyst for the oxidation of straight-chain aliphatic compounds.
In organic synthesis, acidic dichromate oxidizes primary alcohols to aldehydes or carboxylic acids and secondary alcohols to ketones; tertiary alcohols are unaffected. The active species are mostly chromium trioxide species formed in the presence of sulfuric acid.
The change of orange to green shows that the reaction has taken place in classical tests such as distinguishing aldehydes from ketones.
In photomechanical processes, dichromate crosslinks colloids such as gelatin or gum arabic under light and makes them insoluble. While light reduces Cr(VI) to Cr(III), bonds form between the colloid chains and the areas exposed to light harden.
In leather tanning, the actual active species is Cr(III). Dichromate is first reduced to chromium(III) salts; these salts bond with the carboxyl groups in collagen fibers and make the hide resistant to decay.
At the biological level, Cr(VI) can easily cross the cell membrane thanks to its chromate-like structure. Inside the cell, reactive intermediates and free radicals form while it is reduced by molecules such as ascorbate and glutathione.
The resulting Cr(III) forms lasting bonds with DNA and proteins. In scientific publications this process is accepted as the main explanation for Cr(VI) being mutagenic and carcinogenic. Cr(III), on the other hand, is poorly absorbed and has much lower toxicity.
In the environment, Cr(VI) is generally reduced to Cr(III) by organic matter and reducing agents such as iron(II). Cr(VI), which is soluble and mobile, can pose a risk in surface and groundwater.
WHICH SECTORS IS POTASSIUM DICHROMATE USED IN?
Potassium Dichromate has a history of use ranging from analytical chemistry to the leather and pigment industries. Because of hexavalent chromium restrictions, its use has narrowed in many areas today. The main sectors and the function in each are summarized below.
Laboratory and analytical chemistry
It is used as a standard solution in redox titrations, as an oxidizing reagent in chemical oxygen demand determination, as a reference substance in spectrophotometer calibration and as a reagent in classical methods such as alcohol determination.
Pigments and paints
It is used as a chromium source in the production of chromium pigments such as chrome yellow and orange. Chromium compounds also play a role in coloring glass and ceramics.
Leather and tanning
Rather than being a tanning agent directly, it is the starting material in the preparation of chromium(III) salts such as potassium chrome alum.
Photography, lithography and printing
It is used as a light sensitizer in classical printing processes such as dichromated gelatin and gum bichromate. It has also been used in the past in lithography and screen printing.
Wood staining and preservation
Because it reacts with the tannins in wood and gives dark brown tones, especially in species such as mahogany, it has been used in wood staining. Chromium compounds have also been part of some wood preservative systems.
Metal surface treatments
It is used as a chromium(VI) source in chromate conversion coatings, passivation solutions and the preparation of chromic acid. It continues in limited areas such as aerospace and defense.
Organic synthesis and the chemical industry
It is used in syntheses such as the oxidation of alcohols and the preparation of quinones, and also as a catalyst and as an intermediate for chromium compounds.
Pyrotechnics and matches
Owing to its strong oxidizing nature, it has been used as an oxidizer in pyrotechnic mixtures and match-head compositions. These uses are limited today.
Cement and construction (unwanted source)
In cement, hexavalent chromium is not an additive but an impurity originating from raw materials and clinker. For this reason, soluble chromium(VI) in cement has been restricted, and reducing agents such as iron(II) sulfate have been used.
For each of these areas, the product’s grade, documents and regulatory compliance should be evaluated separately.
IS POTASSIUM DICHROMATE USED IN COSMETIC, FOOD AND PHARMACEUTICAL APPLICATIONS?
Cosmetic applications
No. Potassium Dichromate is not used as an ingredient in cosmetic products. Hexavalent chromium compounds are among the substances whose use in cosmetics is prohibited or restricted; for example, chromium(VI) is prohibited under Canada’s cosmetic ingredient list.
The lists of prohibited substances in European Union and Turkish cosmetic legislation should be checked separately. Colorants such as chromium oxide, a trivalent compound, are different substances and are subject to their own regulatory conditions.
In inspection studies in Europe, trace levels of chromium have been detected in decorative cosmetics. This does not mean that Potassium Dichromate is used.
Food applications
No. Potassium Dichromate is not a food additive, has no E code and cannot be added to food directly or indirectly.
Its role in the food and beverage field is analytical. For example, it has been used as a reagent in classical methods such as the determination of alcohol in alcoholic beverages.
In drinking water, 50 µg/L (0.05 mg/L) is used as the guideline value for total chromium by the World Health Organization and in Canada. These values are based on the health effects of hexavalent chromium.
Pharmaceutical applications
No. Potassium Dichromate is not used as an active ingredient or excipient in medicines.
It appears in the medical field in two places. The first is its use as an allergen at a concentration of about 0.25–0.5 percent in petrolatum in skin allergy patch test series to detect chromium allergy.
The second is its role as a reference substance in spectrophotometer verifications within pharmacopoeias. These uses are not pharmaceutical formulations.
The analytical or diagnostic use of a chemical does not mean that it can be used as a food, cosmetic or pharmaceutical ingredient.
INDUSTRIAL APPLICATIONS OF POTASSIUM DICHROMATE
The industrial use of Potassium Dichromate is based on its being a strong oxidizer and a chromium source. The headings below describe the product’s function, reasons for preference and limitations on an application basis.
Titrimetric analysis and primary standard
Potassium Dichromate is used as a source of standard solution in the determination of iron(II) and in the analysis of many reducing substances. Its availability in high purity, its non-hygroscopic nature and the stability of its solutions are the reasons for preference for this purpose.
Because the standard solution can be prepared directly by weighing, no separate standardization is required. The limitation is that chromium is toxic and carcinogenic; waste solutions must be managed separately. Oxidizers such as permanganate, cerium(IV) or iodate can be alternatives.
Chemical oxygen demand (COD) determination
In wastewater, surface water and treatment plant effluents, COD is measured by the dichromate method. The method is based on standards such as Standard Methods 5220 and ISO 6060 and gives oxidizable organic pollution as an oxygen equivalent.
The dichromate method is widespread because it oxidizes a wide range of compounds. On the other hand, it generates waste containing Cr(VI), mercury and silver; this waste must be collected and disposed of separately.
The method cannot be applied to samples with very high chloride concentrations. Total organic carbon measurement, the permanganate index and dichromate-free test kits are complementary options.
Spectrophotometer calibration
Acidic Potassium Dichromate solutions give known specific absorbance values at wavelengths such as 235, 257, 313 and 350 nm in the ultraviolet region, and are therefore used to check the absorbance accuracy of spectrophotometers.
For this use there are ready-made calibration solutions of pharmacopoeial quality and certified crystalline standards from national metrology institutes. If the user prepares their own solution, the purity of the crystal must be documented.
Pigment production
Dichromate is one of the raw materials used as a chromium source in the preparation of chrome yellow and orange pigments such as lead chromate and other chromium pigments.
Pigments containing lead and chromium(VI) are restricted in many regions. Lead-free and chromium(VI)-free pigments such as bismuth vanadate and organic yellows are used as alternatives in this field.
Leather tanning
In the leather industry, Potassium Dichromate is not a tanning agent directly but a starting material used in the preparation of chromium(III) salts. Trivalent salts such as potassium chrome alum are obtained in this way.
Today chrome tanning is mostly carried out with ready-made chromium(III) sulfate. Residual Cr(VI) in tanned hides is limited to 3 mg/kg in leather articles that come into contact with the skin in the EU.
Photography, lithography and screen printing
In classical printing processes such as dichromated gelatin and gum bichromate, Potassium Dichromate is used as a light sensitizer. The areas exposed to light harden and become insoluble, and the remainder is removed by washing.
Today these processes continue mainly in artistic alternative printing and specialty lithography. In industry, photopolymer and diazo-based sensitizers have largely replaced dichromate.
Wood staining and preservation
Potassium Dichromate reacts with the tannins in wood and gives deep brown tones, especially in species such as mahogany. For this reason it has been used in wood staining solutions.
In protective wood impregnation systems, chromium-containing formulations have been used against decay and insects. Because of environmental and health concerns this area has narrowed, and chromium-free copper-based preservatives have become widespread.
Metal surface treatments
Dichromate is a chromium(VI) source in chromate conversion coatings, passivation solutions and the preparation of chromic acid. It provides corrosion resistance and paint adhesion on aluminum, zinc and magnesium surfaces.
Replacing these coatings is difficult in some aerospace and defense applications. For this reason limited use continues. In the EU, Potassium Dichromate is on the authorization list; authorization is required for use.
Many users are moving to chromium(III), zirconium- and titanium-based, molybdate, cerium or silane-based systems.
Organic synthesis
In laboratory and fine chemical synthesis, the oxidation of alcohols to aldehydes, ketones or carboxylic acids and the preparation of quinones such as naphthoquinone are classical applications.
Because of toxicity and waste problems, chromium-free methods such as TEMPO, Swern and Dess–Martin oxidations are preferred in modern synthesis.
Cement and construction
The hexavalent chromium in cement does not come from the deliberate use of Potassium Dichromate but from an impurity originating from raw materials and clinker. Water-soluble Cr(VI) can penetrate the skin in an alkaline medium and cause eczema.
In the EU, soluble Cr(VI) in cement is limited to 2 mg/kg. Reducing agents such as iron(II) sulfate are used to meet this limit. The shelf life of the product depends on the effectiveness of this reducing agent.
CONSIDERATIONS IN THE USE OF POTASSIUM DICHROMATE
Potassium Dichromate is a strong oxidizer, toxic, corrosive and carcinogenic substance. The decision to use it should be made only when it is necessary and suitable conditions are met. The main points to be considered in use:
• Substitutability must be evaluated first. If the same result can be obtained with a less hazardous product, substitution is the priority option; if it cannot be substituted, the use must be justified
• The regulatory status must be verified. Obligations for authorization, restriction and carcinogenic and mutagenic substances in the EU, and obligations under KKDİK and occupational health legislation in Türkiye, must be checked separately
• A grade suitable for the intended use must be selected. There are differences between analytical reagent, primary standard and technical grades in terms of impurity limits and documentation
• Where possible, a closed system or local exhaust ventilation should be used. Weighing and transfer operations should be done in dust-controlled environments such as a fume hood
• Dust and aerosols must not be inhaled. Working with solutions or forms that reduce dust formation should be preferred where possible
• Personal protective equipment must be used. Chemical-resistant gloves, tightly fitting goggles or a face shield, protective work clothing and, when necessary, respiratory protection with high-efficiency particulate filters are required
• It must be kept away from incompatible substances. Violent reactions can occur on contact with reducing agents, organic and combustible materials, hydrazine, hydroxylamine, ethylene glycol and acetone–sulfuric acid mixtures
• Mixing with concentrated acids should be done only under controlled conditions. Heat and toxic gas may form; it must not be mixed with hydrochloric acid
• The product is not flammable but supports combustion. Plenty of water is recommended in a fire; in choosing the extinguishing agent, the product-specific SDS and the emergency plan should be taken as the basis
• Dry sweeping must not be done. Spilled material should be collected after wetting or with a HEPA-filtered vacuum, and cellulose-based absorbents must not be used
• Eating, drinking and smoking at the workplace should be prohibited, work clothing should be left at the workplace and washing facilities should be provided
• Health surveillance and, when necessary, biological monitoring should be planned for employees who may be exposed
• When chromium allergy develops, sensitivity can last for many years. For this reason, preventing skin contact is especially important
• Because of its very toxic aquatic hazard, the product and solutions containing Cr(VI) must not be released into the sewer or the natural environment; waste must be collected separately and disposed of by authorized organizations
This information is for general informational purposes; it does not replace the product-specific SDS and TDS documents.
INITIAL FORMULATION APPROACHES FOR POTASSIUM DICHROMATE
Since Potassium Dichromate is a toxic, carcinogenic and strongly oxidizing substance, no commercial recipe or process instruction is given in this section. The examples below are starting approaches prepared solely to show how the product can be evaluated in low-concentration analytical solutions.
These are not verified commercial recipes, production instructions or final formulas compliant with legislation. The ratios given are example starting levels for preliminary laboratory trials, and the total of each formula is 100%.
The purity of the product used, the solution temperature and other raw materials may change the result. In every application, technical evaluation, occupational safety and relevant regulatory checks must be carried out, and the ratios must be reviewed by experts.
EXAMPLE 1: EVALUATION OF THE CONCENTRATION OF A POTASSIUM DICHROMATE STANDARD SOLUTION FOR REDOX TITRATION
Purpose: To examine the effect of the concentration of the Potassium Dichromate solution to be used in titrimetric analysis on titration volume, end-point sharpness and weighing error.
Starting approach (Formula A, B and C):
Potassium Dichromate (primary standard grade): approx. 0.25%, 0.49% and 0.98%
Demineralized water: approx. 99.75%, 99.51% and 99.02%
Application approach:
• The primary standard grade product is prepared according to the drying and use conditions in the certificate document.
• The required amount is weighed on an analytical balance; weighing is done in a dust-controlled environment, with tightly fitting goggles, gloves and a protective apron.
• The crystal is dissolved in demineralized water and made up to the mark in a volumetric flask.
• Formula B corresponds to a concentration of approx. 0.0167 mol/L (0.1 N); the actual concentration is calculated from the weighed mass and the final volume.
• The solution is used in the titration of a reducing agent such as iron(II) in acidic medium, and the end point is determined with a suitable redox indicator.
• Titration volume, end-point sharpness and repeatability are compared at different concentrations.
• Because the solution and titration waste contain chromium(VI), they must be collected separately, labeled and disposed of by authorized organizations; contact and dust inhalation must be avoided during work.
EXAMPLE 2: EVALUATION OF THE CONCENTRATION OF AN ACIDIC POTASSIUM DICHROMATE SOLUTION FOR SPECTROPHOTOMETER ABSORBANCE CHECKING
Purpose: To examine the effect of the concentration of a dilute acidic Potassium Dichromate solution, used to check the absorbance accuracy and linearity of a spectrophotometer in the ultraviolet region, on absorbance values.
Starting approach (Formula A, B and C):
Potassium Dichromate: approx. 0.003%, 0.006% and 0.012%
Sulfuric acid (in an amount giving a level of approx. 0.005 mol/L): approx. 0.049%
Demineralized water: approx. 99.948%, 99.945% and 99.939%
Application approach:
• The product to be used is selected in high purity and documented quality, in line with the conditions of the pharmacopoeia or national metrology institutes.
• When preparing the dilute sulfuric acid solution, the acid is always added to the water under stirring.
• Potassium Dichromate is weighed, dissolved in the acid solution and made up to volume in a volumetric flask.
• The same acid solution is used as the blank; the absorbance of the solution is measured at wavelengths of 235, 257, 313 and 350 nm.
• The measured values are compared with the expected specific absorbance values and the permitted deviation range.
• Whether absorbance increases linearly with concentration at different concentrations is evaluated.
• In out-of-range results, first the solution preparation steps and then the instrument are checked; ready-made certified standards may be preferred. During work, contact with the solution containing Cr(VI) must be avoided and waste must be collected separately.
EXAMPLE 3: CONCEPTUAL EVALUATION OF THE POTASSIUM DICHROMATE OXIDIZING SYSTEM IN CHEMICAL OXYGEN DEMAND (COD) DETERMINATION
Purpose: To evaluate at a conceptual level which variables affect the result of the dichromate oxidizing system in COD determination, and to create a criterion for method selection.
Starting approach (conceptual variables):
Potassium Dichromate: used at the concentration defined in the method standard; no ratio is given in this text
Strong acid medium: according to the method standard
Silver sulfate: as catalyst
Mercury(II) sulfate: to eliminate chloride interference
Sample: dilution appropriate to the pollution level
Evaluation approach:
• The method is applied according to the current text of the relevant standard (for example Standard Methods 5220 or ISO 6060); detailed concentrations and procedural steps should be taken only from the standard text.
• Chloride content and nitrite and reducing inorganic ion interferences of the sample are evaluated beforehand.
• Results are verified with certified reference solutions and blank tests.
• Repeatability, recovery and measurement uncertainty are calculated.
• The same samples are measured in parallel with a dichromate-free method and the results are compared.
• The work should be carried out in a competent laboratory, in closed and controlled systems; waste containing Cr(VI), mercury and silver must be collected separately and disposed of by authorized organizations.
SIMILAR PRODUCTS AND ALTERNATIVES TO POTASSIUM DICHROMATE
An alternative to Potassium Dichromate does not simply mean choosing another chromium salt. In determining an alternative, oxidizing power, selectivity, stability, regulatory status, waste management and cost must be evaluated together.
POTASSIUM DICHROMATE AND SODIUM DICHROMATE
Sodium dichromate (CAS No 7789-12-0) is the most widely used dichromate salt in industry. Compared with the potassium salt it is far more soluble in water, hygroscopic and often more economical.
Because it is hygroscopic, it is not suitable as an analytical standard; for this reason the potassium salt is preferred in laboratories. Sodium dichromate is also subject to the same carcinogenicity classification and authorization obligations.
POTASSIUM DICHROMATE AND AMMONIUM DICHROMATE
Ammonium dichromate (CAS No 7789-09-5) is an orange-red crystalline, similarly oxidizing and light-sensitive salt. It can be used in place of dichromate in photographic and pyrotechnic applications.
When heated it shows a violent, self-propagating decomposition and carries the same Cr(VI) hazards. For this reason it offers no improvement in terms of safety.
POTASSIUM DICHROMATE AND POTASSIUM PERMANGANATE
Permanganate is self-indicating in titrations and is a very strong oxidizer. However, it is not a primary standard, its solutions decompose over time with light and organic matter, and it needs to be standardized.
Dichromate solutions are much more stable and can be used in chloride-containing media. Permanganate, on the other hand, does not contain chromium(VI) and is therefore advantageous in terms of waste and regulation.
POTASSIUM DICHROMATE AND CERIUM(IV), IODATE, BROMATE
Cerium(IV) sulfate and ammonium cerium(IV) nitrate are titrants that give stable solutions and have an oxidizing power close to or higher than that of dichromate.
Potassium iodate and potassium bromate are used as primary standards because they can be obtained in high purity. None contains Cr(VI); however, each has its own indicator, medium and cost limitations.
POTASSIUM DICHROMATE AND CHROMATE CONVERSION COATING ALTERNATIVES
In surface treatments, chromium(III)-based, zirconium- and titanium-based, molybdate, cerium and silane-based systems are evaluated in place of chromium(VI)-based conversion coatings.
These systems are generally less hazardous. However, they must be tested on an application basis in terms of corrosion resistance, self-healing, electrical conductivity, paint adhesion and process compatibility.
Different coating technologies such as thermal spray, electroless nickel and physical vapor deposition may also be options in some applications.
POTASSIUM DICHROMATE AND OTHER ALTERNATIVES
In leather tanning, there are chromium-free systems based on vegetable, aldehyde-based, synthetic and zirconium, titanium or aluminum salts. They differ in terms of leather properties and cost.
Lead-free inorganic and organic pigments are used in pigments, and chromium-free copper-based preservatives in wood protection.
In organic synthesis, the TEMPO, Swern and Dess–Martin methods are the main chromium-free options for alcohol oxidation.
In COD determination, total organic carbon analysis, the permanganate index and dichromate-free test kits are complementary methods. The method accepted for statutory monitoring must be determined according to the relevant legislation.
No alternative is an exact substitute in every system; in every case a performance test and regulatory check must be carried out.
QUALITY CONTROL AND PURCHASING CRITERIA FOR POTASSIUM DICHROMATE
Although Potassium Dichromate is sold under the same name, its quality and documentation level differ according to the field of use. Analytical reagent and primary standard grades are prepared for laboratories, while technical grades are mostly prepared for industry.
For this reason, in purchasing and incoming inspection the target grade must first be determined, and then the parameters must be selected according to that grade. The expression “technical grade” is not a specification on its own.
Main parameters that can be evaluated in the quality control and purchasing process:
• Purity: In analytical grades mostly at least 99.9 percent, in ACS reagent grade at least 99 percent, in some technical grades at least 99.7 percent is given; the method and limits should be taken from the supplier’s document
• Appearance: It should be homogeneous orange-red crystals or powder. Foreign matter, moisture stains or caking indicate a quality problem
• Water-insoluble matter: In analytical grades generally at most 0.005 percent; in some technical grades approx. 0.05 percent
• Chloride and sulfate: In analytical grade chloride at most 0.001 percent and sulfate at most 0.005 percent; in some technical grades approx. 0.07 percent for chloride and approx. 0.05 percent for sulfate are given
• Sodium and calcium: In analytical grade sodium at most 0.02 percent and calcium at most 0.002 percent; in some technical grades a higher limit for sodium (for example at most 0.5 percent) is seen
• Heavy metals and iron: In analytical grade lead is defined as at most 0.005 percent, and copper and iron as at most 0.001 percent
• Loss on drying: In analytical grade generally at most 0.05 percent
• Primary standard and UV calibration grades: Purity and traceability are documented by certificate; specific absorbance values and solution preparation conditions are stated in the document
• Particle size and form: Crystal or powder; affects dissolution rate and dust formation
• Bulk density: Important for storage and dosing; varies between forms
• Product form: Whether it is solid or solution should be clarified; the classification and transport rules of solutions may differ
• Documents: Batch-based certificate of analysis, current SDS, TDS, REACH information, a supplier statement on whether the intended use falls within the authorization scope, and transport classification
• Shelf life: In dry crystal form it is stable for a long time; the retest date and batch number should be traceable
• Packaging: In laboratory grades, package sizes from approx. 100 g up to 25 kg are seen; package integrity and label information should be checked
Manufacturer typical values and binding product specifications should be distinguished from each other. Typical values are generally for information purposes; the specification in the purchase contract and the batch results in the certificate of analysis should be taken as the basis.
STORAGE AND TRANSPORT OF POTASSIUM DICHROMATE
Potassium Dichromate is stable in dry, closed packaging; however, it is a strong oxidizer, toxic and carcinogenic. Storage conditions must be determined according to these properties.
• Temperature and location: Stored in a cool, dry and well-ventilated place. It should be kept away from heat sources and direct sunlight
• Access: It should be kept in a locked or access-restricted area that unauthorized persons cannot reach
• Moisture: It is not hygroscopic; nevertheless the packaging should be kept closed and protected from wetting and contamination
• Incompatible substances: It must not be stored next to combustible and organic substances, reducing agents, hydrazine, hydroxylamine, ethylene glycol, acetone–sulfuric acid mixtures, strong acids and some powdered metals
• Fire safety: The product itself does not burn but supports combustion. Packages heated in a fire are dangerous and toxic smoke may be released
• Packaging: It should be stored in its original packaging with labels intact. The packaging material should be selected according to the supplier’s recommendation
• Separate storage from food and feed: It must not be stored together with food, beverages and feed, and must not be transported in the same vehicle
• Ventilation and dust: Dust formation should be prevented during transfer, and a cleaning routine that prevents contamination should be applied in the storage area
• Shelf life: In dry crystal form it is stable for a long time. Manufacturers may state a retest date in their documents; the life of solutions varies with concentration and conditions
• Transportation: Solid Potassium Dichromate is transported as a dangerous good. In safety data sheets UN 3086 (toxic solid, oxidizing, n.o.s.; class 6.1, subsidiary hazard 5.1) is most often seen. Different numbers such as UN 3087, UN 3288 or UN 3085 also appear in some documents
• Transport classification: These differences may depend on product form, packing group, document date and regional regulation. Before shipment, the supplier’s current SDS and the applicable transport legislation should be taken as the basis
• During transport: Package integrity must be preserved, it must not be loaded together with combustible and reducing substances, and in case of spillage it must be collected without creating dust. The substance may also be classified as a marine pollutant
SAFETY INFORMATION ON POTASSIUM DICHROMATE
Potassium Dichromate is a highly hazardous substance. Classification may show small differences between the safety data sheets of different manufacturers; however, the classes oxidizing solid, acutely toxic, corrosive, sensitizing, mutagenic, carcinogenic and toxic to reproduction are commonly reported.
The information below is for general informational purposes and does not replace the manufacturer-specific safety data sheet. Each supplier’s own SDS must be taken into account.
Main safety topics:
• Hazard classes: Commonly reported are oxidizing solid (H272), acute toxicity (H301, H312, H330), skin corrosion (H314), respiratory and skin sensitization (H334, H317), mutagenicity (H340), carcinogenicity (H350), reproductive toxicity (H360), organ damage through repeated exposure (H372) and long-term hazard to the aquatic environment (H410)
• Classification differences: Some documents additionally include serious eye damage (H318). For carcinogenicity some authorities use category 1A, while most SDSs use category 1B
• Acute toxicity: The oral LD50 value in rats is reported as approx. 25 mg/kg. Ingestion can cause severe gastrointestinal damage, circulatory collapse and kidney damage
• Inhalation: Inhaling dust is very toxic and irritates the respiratory tract. With repeated exposure it can cause asthma-like reactions and perforation of the nasal septum
• Skin contact: It is corrosive. It can cause painless, deep “chrome ulcers” and allergic contact dermatitis. The allergy can last for many years
• Eye contact: It can cause serious eye damage. In case of contact, rinse with plenty of water for at least 20–30 minutes and seek medical help immediately
• Cancer: IARC classifies chromium(VI) compounds as carcinogenic to humans (Group 1). The US National Toxicology Program also lists these compounds among known human carcinogens. Lung and nasal–sinus cancers are established risks
• Reproductive and genetic effects: Genetic damage and the risk of harming fertility or the unborn child are reported
• Fire and reactivity: Not combustible but supports combustion. Fire can break out on contact with organic materials; it reacts violently with hydrazine and hydroxylamine
• Occupational exposure limits: For Cr(VI), US OSHA is 5 µg/m³ over 8 hours, and the NIOSH recommendation is 0.2 µg/m³. In the EU the binding limit value is 0.005 mg/m³ as chromium. It varies by country; current limits in Türkiye should be checked separately
• Personal protective equipment: Chemical-resistant gloves, tightly fitting goggles or a face shield, protective clothing and, when necessary, P3 or FFP3 class respiratory protection should be used
• Spills: It must not be dry swept; it should be collected after wetting or with a HEPA-filtered vacuum and kept away from combustible materials. The area should be isolated and unauthorized entry prevented
• Environment: It is very toxic to aquatic organisms. Hexavalent chromium is mobile and can enter water sources. For total chromium in drinking water a guideline value of 50 µg/L is used
• Waste: Waste containing Cr(VI) must be managed as hazardous waste. Processes such as reduction and precipitation should be carried out only in authorized facilities
• In case of exposure: The affected person should be moved to fresh air, contaminated clothing removed, and skin and eyes washed with plenty of water. If swallowed, the mouth should be rinsed, vomiting should not be induced, and a health facility or poison information center (114 in Türkiye) should be contacted immediately
• Health surveillance: Regular health surveillance and, when necessary, biological monitoring such as measurement of total chromium in urine are applied for employees who may be exposed
WHAT SHOULD BE CONSIDERED WHEN BUYING POTASSIUM DICHROMATE?
To choose the right product, the product identity must first be clearly determined. Because potassium dichromate can be confused with potassium chromate, sodium dichromate, ammonium dichromate and chromium trioxide, a request that only says “dichromate” or “chromium salt” is insufficient.
In the request, the product name Potasyum Dikromat or Potassium Dichromate, CAS number 7778-50-9 and EC number 231-906-6 should be stated together.
Main points to be considered when buying:
• Intended use and regulation: The purpose and country of use should be clarified; whether the use falls under authorization or restriction should be verified together with the supplier
• Grade: Which of analytical reagent, ACS, primary standard, UV calibration or technical grades is required must be clarified
• Technical specifications: Purity, water-insoluble matter, chloride, sulfate, sodium and heavy metal limits should be requested explicitly
• Form: Whether a solid product or a solution is required; the crystal or powder form should be chosen in terms of dissolution rate and dust formation
• Packaging and logistics: Net quantity, packaging type and packaging, labels and transport documents suitable for dangerous goods transport must be determined
• Batch consistency: The certificates of analysis and physical appearance of successive batches should be compared
• Documents: SDS, TDS, COA, REACH information and a supplier statement on the intended use should be requested
• Supplier’s technical support: Information support on safe handling, storage and application should be evaluated
• Origin and manufacturer: Transparency of manufacturer information and traceability may be requested
• Buyer-side preparation: Locked storage, separation from incompatible substances, ventilation, protective equipment and waste management capabilities should be planned in advance
• Total cost of supply: In addition to the unit price, the cost of documentation, dangerous goods transport, storage, protective equipment, health surveillance and waste disposal should be calculated together
When comparing prices, one should look not only at the price per kilogram but also at the grade, the level of documentation, regulatory compliance and the security of supply.
SUPPLY OF POTASSIUM DICHROMATE FROM ATAMAN KİMYA
Potassium Dichromate is a product evaluated as an oxidizer and chromium source in fields such as laboratory and analytical chemistry, pigments, leather and metal surface treatments. There is a product page for Potassium Bichromate on the ATAMAN KİMYA website.
For companies planning to buy the product, it is important to clarify the grade suitable for the intended use, the technical specifications, the regulatory conditions and the required documents before ordering.
Companies that want to get information about the supply of Potassium Dichromate from ATAMAN KİMYA can request information on product suitability, current supply status, packaging options and price quotation by sharing their fields of use and technical needs.
The current stock status, origin, grade, technical specifications, packaging, transport classification and regulatory conditions for the intended use of the product should be confirmed from ATAMAN KİMYA before ordering.
Sharing the following information in a quotation request makes it easier to evaluate the correct Potassium Dichromate product:
• Sector of use and final application
• Requested grade: analytical reagent, ACS, primary standard or technical
• Requested product form: crystal or powder
• Limit values such as purity, water-insoluble matter, chloride, sulfate and sodium
• Regulatory status for the intended use and, if available, authorization information
• Process or analysis method used
• Estimated order quantity
• Desired packaging type
• Requested technical documents
• If available, the TDS or COA information of the current product
FREQUENTLY ASKED QUESTIONS ABOUT POTASSIUM DICHROMATE
What is Potassium Dichromate?
Potassium Dichromate is a strong oxidizer with the formula K₂Cr₂O₇, orange-red crystals, soluble in water and containing hexavalent chromium. It is used in laboratory titrations, in chemical oxygen demand determination, in spectrophotometer calibration and in some industrial fields.
What does Potassium Dichromate mean?
The name dichromate refers to the Cr₂O₇²⁻ anion, which contains two chromium atoms; potassium is the metal ion that forms the salt. The name chromium is derived from the Greek word meaning color and refers to the colored nature of its compounds. The old name bichromate is still used in trade.
What is the CAS number of Potassium Dichromate?
The CAS number is 7778-50-9. Solutions and mixtures may be offered under different registrations and classification.
What is the EC / EINECS number of Potassium Dichromate?
The EC number is 231-906-6. The index number in the European Union classification record is 024-002-00-6.
What is the chemical formula of Potassium Dichromate?
Its chemical formula is K₂Cr₂O₇. Its molecular weight is about 294.18 g/mol.
How much chromium does Potassium Dichromate contain?
It contains about 35.4 percent chromium by mass, all of which is hexavalent chromium. For this reason the product must be evaluated as a Cr(VI) compound even if its chromium content appears low.
Is Potassium Dichromate used in cosmetics?
No. Hexavalent chromium compounds are not used in cosmetic products and are among the prohibited or restricted substances in many countries. Colorants such as trivalent chromium oxide are different substances.
Is Potassium Dichromate used in food or pharmaceuticals?
No. It is not a food additive, has no E code, and is not used as an active ingredient or excipient in medicines. Its role in the food and pharmaceutical field is limited to being an analytical reagent and a skin allergy patch test substance.
What is the difference between Potassium Dichromate and sodium dichromate?
Both contain the same dichromate anion. Sodium dichromate is more soluble in water, hygroscopic and more widespread in industry. Potassium dichromate is preferred in laboratories and standard solutions because it is not hygroscopic.
What is Potassium Dichromate used for?
As a strong oxidizer and chromium(VI) source, it is used in titrations, in chemical oxygen demand determination, in spectrophotometer calibration, in pigment production, in photographic printing, in wood staining and in metal surface treatments.
Which sectors is Potassium Dichromate used in?
It is used in the laboratory and analytical chemistry, environmental and water analysis, pigments and paints, leather, photography and printing, wood, metal surface treatments and organic synthesis sectors. In many areas its use has declined because of chromium(VI) restrictions.
How does Potassium Dichromate carry out oxidation?
In acidic medium the dichromate ion accepts six electrons and is reduced to two Cr³⁺ ions. At the same time the reducing agent in the medium is oxidized. The orange color turns green.
What is Potassium Dichromate good for?
It is good for forming standard solutions in redox titrations, for measuring organic pollution as an oxygen equivalent and for checking the accuracy of ultraviolet spectrophotometers. In industry it is also used as a chromium source and oxidizer.
How does Potassium Dichromate work in COD analysis?
In strong sulfuric acid medium at high temperature it oxidizes the organic matter in the sample. The amount of unconsumed dichromate is measured, and the amount consumed gives the COD value as an oxygen equivalent. Mercury(II) sulfate supports chloride interference control and silver sulfate supports the oxidation of some compounds.
Is Potassium Dichromate soluble in water?
Yes. A solubility of approx. 115–125 g/L at 20 °C is reported in most documents, and solubility increases with temperature. Its aqueous solution is orange and acidic. It is insoluble in ethanol.
How much Potassium Dichromate is used in COD analysis?
The amount depends on the method. The solution concentration and sample volume are defined in the relevant standard method text. For this reason it would not be correct to give a fixed amount; the application should be carried out according to the method standard.
Is Potassium Dichromate a hazardous substance?
Yes. It is an oxidizing, acutely toxic, corrosive, sensitizing, mutagenic, carcinogenic and reproductively toxic substance. It is also very toxic to aquatic life. It should be used only by trained personnel with appropriate protective measures.
Why can Potassium Dichromate cause allergy?
Cr(VI) can penetrate the skin and, while being reduced to Cr(III), which binds to skin proteins, can cause a delayed-type allergic reaction. Sources such as leather, cement and matches are common in chromium allergy. Sensitivity can last for many years.
Is Potassium Dichromate registered under REACH?
The substance falls under REACH; it has been identified as a substance of very high concern and included in the authorization list (Annex XIV). The latest application date was 21 March 2016, and the date from which authorization is required for use was set as 21 September 2017. The registration and authorization status of a specific supplier must be confirmed with the supplier.
What is the physical appearance of Potassium Dichromate?
It is in the form of orange-red, odorless crystals or crystalline powder. Its solution is orange; it turns yellow in alkaline medium and green when reduced.
What is the UN number of Potassium Dichromate?
For the solid product, UN 3086 is most often seen in safety data sheets. Different numbers such as UN 3087, UN 3288 or UN 3085 are also found in some documents. The supplier’s current SDS should be checked before shipment.
Why are chloride, sulfate and sodium impurities important in Potassium Dichromate?
These impurities can originate from the production route and lower the purity. They affect the concentration calculation in standard solutions and the result in sensitive analyses and processes. For this reason, limits appropriate to the grade should be verified from the COA.
What does the price of Potassium Dichromate depend on?
Price varies according to grade, purity, product form, packaging, order quantity, origin, certification, raw material costs and logistics conditions. Primary standard and analytical grades are priced differently from technical grades. Dangerous goods transport also affects the cost.
Is there an alternative to Potassium Dichromate?
Yes. Permanganate, cerium(IV), iodate and bromate in analytical applications; chromium(III), zirconium, titanium, molybdate and cerium-based systems in surface treatments; and chromium-free systems in tanning, pigments and wood protection can be alternatives. None is a direct substitute in every system.
How should Potassium Dichromate be stored?
It should be stored in a cool, dry and ventilated place, in a locked area, in its closed original packaging, separate from reducing, combustible and organic substances, and from food and feed.
Which documents should be requested when buying Potassium Dichromate?
SDS, TDS and batch-based COA are the basic documents. In addition, REACH information, a supplier statement on whether the intended use falls within the authorization scope, transport classification and, for primary standard grades, a traceability certificate may be requested.
Which technical specifications are important when buying Potassium Dichromate?
Purity, water-insoluble matter, chloride, sulfate, sodium, calcium, iron and heavy metal limits, loss on drying, form, particle size, bulk density and packaging are important.
POTASSIUM DICHROMATE – TECHNICAL SUMMARY
Chemical name: Dipotassium dichromate; dipotassium salt of dichromic acid
Common name: Potasyum Dikromat, Potassium Dichromate, Potassium bichromate
CAS No: 7778-50-9
EC / EINECS No: 231-906-6
Molecular formula: K₂Cr₂O₇
Molecular weight: 294.18 g/mol
Chemical class: Inorganic dichromate salt; hexavalent chromium compound
Physical appearance: Orange-red, odorless crystals or crystalline powder
Main properties: Strong oxidizer, not hygroscopic, soluble in water at approx. 115–125 g/L at 20 °C, melts at approx. 398 °C, decomposes above approx. 500 °C, density approx. 2.68 g/cm³
Main functions: Oxidizer, titration standard, chromium(VI) source, intermediate for chromium(III) salts
Important application areas: Laboratory and analytical chemistry, chemical oxygen demand determination, spectrophotometer calibration, pigments, leather, photography and printing, wood, metal surface treatments
Critical parameters for quality control: Purity, water-insoluble matter, chloride, sulfate, sodium, calcium, iron and heavy metals, loss on drying, form, documents appropriate to the grade
Storage: In a cool, dry, locked and well-ventilated area; separate from reducing, combustible and organic substances, and from food and feed
Regulation: Oxidizing solid, acutely toxic, corrosive, mutagenic, carcinogenic and reproductively toxic substance; substance of very high concern and on the authorization list under REACH; dangerous good in transport; conditions of use and transport should be confirmed from the supplier and current legislation.
