Chromium III Nitrate: Formula, Properties, Uses

Chromium III nitrate refers to the group of inorganic compounds which comprises chromium, nitrates, and varying amounts of water content. Cr(NO₃)₃ or CrN₃O₉ is the molecular formula of this compound in the anhydrous form and Cr(H₂O)₆](NO₃)₃•3H₂O in the hydrous form. It most commonly occurs in a dark violet-colored hydrate solid, even though there is an anhydrous form in green. It has very limited uses in the industry where its mostly used to prepare dyes and in the academic laboratories sector, it is used in the process of synthesis of chromium complexes.

Key Terms: Cr(NO₃)₃, Chromium trinitrate, Inorganic compound, Hydrous blue-violet, Anhydrous purple, Chromium compound, Aqua ligand bonds, Anhydrous form

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Chemical Formula and Structure

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The IUPAC name of Chromium trinitrate is chromium(3+);trinitrate. Chromium III nitrate is also known as Chromium trinitrate has the chemical formula of Cr(H₂O)₆](NO₃)3•3H₂O in its hydrous form and Cr(NO₃)₃ in its anhydrous form. This easily highlights the complicated structure of this inorganic compound. These types of complicated structures are a common occurrence in hydrated metals such as Chromium III Nitrate.

The compound centers around a chromium atom with a number 6 aqua(water) ligand bonds and the remaining volume of the solid is owed to the 3 nitrate anions and 3 molecules of water of crystallization.

The chemical composition of Chromium III Nitrate consists of:

• Chromium is present in 21.84%
• Nitrogen is present at 17.65%
• Oxygen is present at 60.50%

Synonyms

1. Chromic nitrate
2. Chromium trinitrate
3. Chromium nitrate nonahydrate
4. Chromonitric acid
5. Nitric acid chromium salt

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Preparation of Chromium III Nitrate

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There are two methods of preparing Chromium III Nitrate

1. First method is a simple method that involves dissolving chromium oxide in nitric acid.
2. The second method generates the more stable form of Chromium III Nitrate in its concentrated, aqueous forms of chromium (III) nitrate with certain carboxylic trans-acids. This is prepared by heating the trans-acid with chromium (III) nitrate and with an alkali, the ratios of the reactants being 1 gram-atom of chromium to 1.0-1.5 gram-equivalents of alkali to 0.4-0.6 mole of the trans-acid.

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General Properties of Chromium III Nitrate

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• The appearance of Chromium III Nitrate is of Blue-violet in the anhydrous form and of purple crystals in the hydrous form.
• The melting point of Chromium III Nitrate is 60.06 °C (140.11 °F; 333.21 K)
• The boiling point of Chromium III Nitrate is above 100 °C (212 °F; 373 K)
• It is soluble in water
• The density of this compound is 1.85 g/cm³
• The Molar mass of the compound is 238.011 g/mol in the anhydrous form and 400.21 g/mol in the nonahydrate form.
• It has no odor.
• It is stable under normal conditions.
• It is incompatible with Oxidising metals, Aluminium, and Magnesium metals.
• It has a fair shelf life and is recommended to be stored in a cool, dry place strictly avoiding direct contact with heat and ignition sources.
• It is a strong oxidizing agent. When heated it releases acrid fumes.

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Uses of Chromium Trinitrate

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• Solutions of these complexes are useful in the preparation process of fabricating glass-fiber/polyolefin composites,
• These complexes are very good coupling agents.
• These are used as corrosion inhibitors and anti-scaling agents.
• It is used to prepare plating agents and surface treating agents.
• It is also used as process regulators.
• It is used in preparing automotive care products.
• It is used in preparing fabricated metal product manufacturing.
• It is used in paint and coating manufacturing.
• It is used in petrochemical manufacturing.
• It is used in synthetic dye and pigment manufacturing.
• It is also used in the process of pickling.
• It is also used to prepare alkali-free metal catalysts.

Safety hazards

Direct contact to the skin or eyes can cause skin irritation, itching, redness, burning, tearing, conjunctivitis. Inhalation can cause coughing, wheezing and shortness of breath. When ingested it is slightly toxic and can cause damage to the liver and kidneys and can cause burning sensation of the mouth and throat and cause vomiting and abdominal pain. It is also an Ecotoxic substance, to both the terrestrial and aquatic habitats as it contains chromium, a heavy toxic metal. Hence it must never be released to the environment.

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Things to remember

• The chemical formula for Chromium trinitrate is CrN₃O₉ in anhydrous form and Cr(H₂O)₆](NO₃)₃•3H₂O in non-hydrated form.
• The IUPAC name is chromium(3+);trinitrate.
• Consists of 6 aqua ligand bonds around a central chromium atom.
• It is prepared by dissolving chromium oxide in nitric acid.
• It is a strong oxidising agent.

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