Chromic acid may be a compound during which the trioxide is that the anhydride. A mix made by adding concentrated vitriol to a dichromate is often referring to as chromic acid. The mixture may contain a spread of compounds like solid chromium trioxide. During this chapter, students will learn the chromic acid formula and their different properties with chemical reactions.
Chromic Acid Formula
It may be a chromium oxoacid. It’s the conjugate acid of hydrogen chromate. And it features chromium in an oxidation number of +6 (or VI). It’s a robust and corrosive oxidant. The molecular acid formula of it is H2CrO4. It has much in common with vitriol, H2SO4. Classification of both is as strong acids. H2CrO4 ⇌ [HCrO4]− + H+
- Molecular Formula = H2CrO4
- IUPAC name = Chromic acid
- The Simplified molecular-input line-entry system (SMILES) = O[Cr](=O)(=O)O
Its appearance is dark red crystals. Its density is 1.201 g cm−3. The melting point of chromic acid is 197 °C (387 °F; 470 K) and the boiling point is 250 °C (482 °F; 523 K). Chromate and dichromate are the conjugate bases of it.
It is an intermediate in chromium plating. It is also used in ceramic glazes and coloured glass. Because a solution of it in sulfuric acid is a powerful oxidizing agent, it can be used to clean laboratory glassware. Particularly of otherwise insoluble organic residues is its other use.
Preparation of Chromic acid
The addition of chromic trioxide to water gives molecular acid.
CrO3 + H2O ⇌ H2CrO4
But in practice, the reverse reaction occurs when molecular acid is dehydrated. This is often what happens when concentrated vitriol is added to a dichromate solution. At first, the colour changes from orange to red (chromic acid). Then crimson crystals of chromium trioxide precipitate from the mixture, without further colour change.
The colours are because of LMCT transitions. Chromium trioxide is the anhydride of molecular acid. It’s a Lewis acid and may react with a Lewis base. As pyridine reacts during a non-aqueous medium. Collins reagent is an adduct of chromium trioxide and pyridine used for diverse oxidations. It (H2CrO4) oxidizes alcohols in aqueous solutions. It reacts with alcohol to make a chromic ester. And during which the alcohol oxygen atom bridges the carbon and chromium atoms.
Solved Examples for Chromic Acid Formula
Q1] Explain Jones’s reagent and its reaction with reference to acid.
Solution: It is in aqueous vitriol and acetone is understood because of the Jones reagent. It’ll oxidize primary and secondary alcohols to carboxylic acids and ketones respectively, while rarely affecting unsaturated bonds.
2HCrO4− + 3RR’C(OH)H + 8 H+ + 4H2O → 2[Cr(H2O)6]3+ + 3RR’CO.
Q2] Tell the generation of Pyridinium chlorochromate and write a reaction.
Solution – It is generated from chromium trioxide and pyridinium chloride. This reagent converts primary alcohols to the corresponding aldehydes (R–CHO). Chromyl chloride CrO2Cl2 may be a well-defined molecular compound that’s generated from acid.
C5H5N + HCl + CrO3 → [C5H5NH][CrO3Cl]
The formation of chromyl chloride (CrO2Cl2) fume during the making of the aforementioned solution occurs. And minimization helps to simply change the order of addition. The chilly solution of pyridine in acid was added to solid chromium trioxide under stirring.
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