DICHROMIC ACID: FORMULA AND CHARACTERISTICS - SCIENCE - 2024

The dichromic acid is an unstable oxidizing dibasic acid known only in solution and as dichromatic salts (such as potassium dichromate) whose color is orange or red.

Its chemical formula is H2Cr2O7 and it can be obtained from two molecules of chromic acid, with the loss of one molecule of water. It is hygroscopic and absorbs humidity from the environment.

2 H2CrO4 -> H2Cr2O7 + H2O

The ions that make up dichromic acid are:

Dichromate anion Cr2O7 -2 and two cations H +

A compound of dichromic acid is potassium dichromate which is a good oxidant.

Molecular formula

Cr2H2O7

Chemical names

Dichromic acid; Dichromic acid (VI); Chromic acid (H2Cr2O7); 13530-68-2; Dichromic acid (H2Cr2O7)

Chemical and physical properties

Calculated properties

-Molecular weight: 218.001 g / mol

-Hydrogen donor links: 2

-Hydrogen bond acceptor: 7

- Revolving bond account 2

-Exact mass 218.0039 g / mol

-Monoisotopic mass 217.861 g / mol

-Count of heavy atoms 9

-Formal position 0

-Complexity 221

-Number of isotopic atoms 0

Potassium dichromate

Potassium dichromate is a dichromic acid that has a wide range of uses, it acts as an oxidant in many chemical and industrial applications and in the dyeing, staining and tanning of leather.

It is also used medically as an external antiseptic or astringent and is present in some veterinary drugs. Potassium dichromate is considered highly toxic and is a corrosive poison if ingested internally.

For this reason, it must be handled with extreme care. The compound is a crystalline ionic solid and has a very bright reddish-orange color.

characteristics

Potassium dichromate is odorless, its boiling point is 500 degrees Celsius. Potassium dichromate has a melting point of 398 degrees Celsius and a molecular weight of 294.18 grams per mole.

Potassium dichromate can be classified as a hexavalent chromium compound due to its oxidation state. The oxidation state is a calculated number that indicates how many electrons are lost or gained in the atom of a compound.

If the oxidation state is positive, there was a loss of electrons. Negative oxidation states indicate a gain of electrons for a particular atom. Hexavalent chromium compounds, such as potassium dichromate, contain the element chromium in its 6+ oxidation state.

Applications

Potassium dichromate is a chemical compound typically used as an inorganic chemical reagent for industrial and laboratory processes. This chemical is also used to produce shoe polishes, glues, paints, and waxes. It is also commonly used in the laboratory as an analytical reagent, and potassium dichromate is also used in industry.

The construction industry uses this chemical in cement products to improve density and texture. Certain woods can change their appearance (or color) in the presence of potassium dichromate. This is especially useful when looking for mahogany or hardwood floors to show their brightest colors.

Other uses for potassium dichromate include:

• Leather tanning for footwear
• Oxidizing agent in the photographic printing process
• Cleaning glassware or etching glassware.

Warnings

Potassium dichromate must be kept away from all flammable materials. Otherwise, you may have an explosive situation to deal with.

There is great debate about the real health dangers of potassium dichromate. This compound and all other dichromates are considered cancer-causing agents or carcinogens by the National Institute for Occupational Safety and Health (NIOSH), the US federal agency that conducts research and recommendations for the prevention of work-related illnesses and injuries..

However, the US Environmental Protection Agency's Office of Pesticide Programs has classified potassium dichromate as most likely non-carcinogenic to humans.

The compound can be easily dispersed through the air, making the inhalation hazard one of the greatest hazards associated with it.

Long-term exposure to the chemical through inhalation can cause asthma. The chemical is also corrosive to the eyes, skin, and respiratory tract and may cause kidney and liver damage if ingested.

Ammonium dichromate

Molecular formula

(NH4) 2Cr2O7 or Cr2H8N2O7

Chemical names

Ammonium dichromate; Ammonium dichromate; 7789-09-5; Diammonium dichromate; Ammonium (VI) dichromate; Ammonium (VI) dichromate

characteristics

Ammonium dichromate is also a salt of dichromic acid and is a bright red-orange crystalline solid. It ignites easily and burns producing a voluminous green residue. If heated in a closed container, the container may break due to decomposition of the material.

It can also act as a strong oxidizing agent if mixed. It is soluble in water and is odorless. Ammonium dichromate is a very strong oxidant that is frequently used for pyrotechnic compositions as a catalyst. It has also been commonly used in photography and lithography.

Ammonium dichromate is a good source of pure nitrogen in the laboratory and is used as a catalyst for the catalytic oxidation of ammonia. It is also used to fix dyes and in the manufacture of photosensitive films acting as a photoactive.

Sodium dichromate

Molecular formula

Na2Cr2O7 or Cr2Na2O7

Chemical names

Sodium dichromate; Celcure; Soda dichromate; Disodium dichromate; Sodium dichromate (VI)

characteristics

Sodium dichromate is an orange to red, inorganic crystalline compound that emits toxic chromium fumes when heated. Sodium chromate can be converted to dichromate acid by a continuous process with sulfuric acid, carbon dioxide, or a combination of these two.

Its molecular weight is 261,965 g / mol. It is highly corrosive and is a strong oxidizing agent. It is used primarily for the production of other chromium compounds and is also used in metal treatments, wood preservatives and as a corrosion inhibitor.

Warnings

Sodium dichromate primarily affects the respiratory system, causing ulcerations, bronchitis, pneumonia, and asthma, as well as the gastrointestinal tract, liver, kidneys, and immune system.

It is a carcinogenic substance and is associated with risks of developing lung cancer and cancer of the nasal cavity. Sodium Dichromate can be irritating to the skin, eyes, and mucous membranes.

Applications

It is used as a corrosion inhibitor, and in the manufacture of other chemicals.

Health hazards

Dichromatic acid is toxic by ingestion. Inhaling powdered dichromatic acid is also toxic. Dichromatic acid exposed to fire can produce irritating, corrosive and / or toxic gases. Contact with the substance can cause severe burns to the skin and eyes.

Fire danger

Dichromatic acid accelerates burning when involved in a fire. It can explode from heat or contamination. They react explosively with hydrocarbons (fuels). It can ignite fuels (wood, paper, oil, clothing, etc.). Containers may explode when heated.

Other uses

In addition to the uses of ammonium, sodium, and potassium dichromates discussed above, dichromic acids are used in chrome plating to protect metals from corrosion and to optimize paint adhesion.

References

1. UK Laboratory Chemicals. (2015). Ammonium Dichromate. 12-24-2016, from Ammonium Dichromate Store Website: ammoniumdichromate.co.uk.
2. National Center for Biotechnology Information. PubChem Compound Database; CID = 24600. Website: pubchem.ncbi.nlm.nih.gov.
3. Reid. D.. (2003). Potassium Dichromate. 12-24-2016, from Study.com Website: study.com.
4. ChemicalBook. (2016). Dichromic acid. 12-24-2016, from Chemical Land Website: chemicalbook.com
5. Chemistry Web. (2016). Molar mass 12-24-2016, from Quimicaweb.net Website: quimicaweb.net.
6. NIOSH Education and Information Division. (2012). National Institute for Occupational Safety and Health (NIOSH). 12-24-2016, from NIOSH Website: cdc.gov.