All About Chromic Acid
Chromic acid is a really strong oxidizing agent that is brought into use for oxidising diverse classes of organic compounds. The most common of these compounds are alcohols. Also, chromic acid is used to designate a mixture that is prepared by mixing dichromate and concentrated sulphuric acid. This type of acid is used as a cleaning mixture for washing glass. It can also refer to the molecular class, H2CrO4. This molecular acid has lots in common with sulphuric acid, H2SO4. Chromic acid is also known by the name of Tetraoxo Chromic acid or Chromic(VI) acid.
Chromic Acid Formula
Chromic acid is the conjugate acid of hydrogen chromate and it possesses chromium in an oxidation number of +6 (or VI). The chromic acid formula is H2CrO4:
IUPAC Name: Chromic Acid.
Chronic Acid Formula: H2CrO4.
The Simplified Molecular-Input Line-Entry System (SMILES): O[Cr](=O)(=O)O
Density: 1.201 g cm.
Melting Point: 197 °C.
Chromic Acid Boiling Point: 250 °C,
Chromic Acid Molecular Weight: 118.01 g/mol
Chromic Acid Preparation
Since chromic acid is known to be highly toxic, it is advisable not to make large portions of it and then store it for a larger period of time. Also, when you are working with any reagent, it is always better to wear proper equipment, for example, gloves, coat, etc. Besides, make sure that you ventilate the room where the acid is to be prepared properly.
Step 1: Get a clean litre flask or a beaker. Fill the beaker with 20 grams Sodium dichromate (Na2Cr2O7) or potassium dichromate (K2Cr2O7).
Step 2: Add some water to the beaker or the flask and then stir it using a glass stirring rod in order to make a paste.
Step 3: when you are stirring, pour 300 ml of concentrated sulfuric acid (H2SO4 (aq)) to the beaker.
Step 4: Pour this prepared chromic acid to a glass container having a stopper. Make sure that you put a label to this beaker and also put the date when it was made.
Chromic Acid Structure
The chromic acid structure is as follows:
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The chromic acid structure includes chromium having an oxidation state of +6 (or VI). Also, the chromic acid splits as:
H2CrO4 ⇌ [HCrO4]- + H+
Different Uses of Chromic Acid
Chromic acid is used as an intermediate for the chromium plating process.
It is also used for coloured glasses and ceramic glazes.
Chromic acid is also used for cleaning laboratory glassware.
It was also used as a hair dye in the year 1940.
It can be used for brightening raw brass and it is thus also used in the instrument repair field, especially the musical instrument repair industry.
It is used as a bleach in photographic reversal procedure.
The said chromic acid can oxidise different forms of organic compounds. Thus, you can find diverse variants being created for this particular reagent. It is also referred to as the Jones reagent in different aqueous sulfuric acid as well as acetone. This oxidises primary as well as secondary alcohols into ketones and carboxylic acids.
Health Hazards of Chromic Acid
Chromic acid which comes under hexavalent chromium compounds is highly toxic as well as carcinogenic. Thus, chromic acid oxidation is used mainly in the aerospace field and not in any other industry. This acid is a strong oxidiser and can react violently if you combine it with some easily oxidisable substance and can even cause some explosion.
Chromic Acid Reactions
Chromic acid can oxidise different types of organic compounds and thus diverse reagent variations can be developed:
Chromic acid in acetone and sulfuric acid is called Jones reagent.
Collins reagent is basically an adduct of pyridine and chromium trioxide which is used for different oxidations.
Chromyl chloride or CrO2Cl2 is also a molecular compound that can be generated from chromic acid.
FAQs on Chromic Acid
Question 1: What are the Hazards of Chromic Acid?
Answer: Chromic acid can have a hazardous effect on your skin. It can also cause reproductive damage and cause irritations in your eyes. It can cause eye damage as well. It can also cause wheezing and shortness of breath when consumed. If you breathe in chromic acid, it can also cause a skin allergy causing some itching as well as skin rashes. Chromic acid can be highly fatal on absorption, swallowing, and when in contact with skin. It can lead to severe eye damage as well as skin burns when it touches the human skin.
Question 2. How can you Identify Chromic Acid?
Answer: You can identify chromic acid through its colour and state. It is dark and purplish while being odourless. It is also in the sand-like solid state. Chromic acid is used for chromium plating, medicines, and paints. Since it is a strong acid and is used as a reagent for the process of oxidising alcohols to ketones as well as carboxylic acids, it is best advisable to do the chromic acid test in a reaction vessel. The reason is that it may cause hazardous effects when coming into contact with the human body. Do not make use of a bottle to disperse the acid.
