Carboxylic Acid Lewis Structure: Drawing and Detailed Explanation

Carboxylic acid Lewis structures are a very significant family of organic compounds. This article depicts the structural details of the carboxylic acid group along with their elaborate explanation.

Carboxylic acid Lewis structure is represented as R-COOH . The carbon share its 2 electrons with 1 oxygen atom forming a double covalent bond. The rest 2 electrons are shared with other oxygen atoms and the R chain. The hydrogen shares its 1 electron with oxygen thereby providing the desired carboxylic acid Lewis structure.

In the carboxylic acid Lewis structure, a functional group is a carboxyl group (-COOH). It is usually a carbonyl group (C=O) and a hydroxyl group (-OH) joined together with carbon. Here the carbonyl group represents a double covalent bond and the hydroxyl group represents the single covalent bond.

Carboxylic Acid Lewis Structure representation

The carboxylic acid Lewis structure general formula as mentioned above is R-(CO)OH where R can be an alkyl or aryl chain. If the R side chain is an alkyl group then it is called aliphatic carboxylic acid. Similarly, if the R side chain is an aryl group then it is called aromatic carboxylic acid. The carboxyl group is the main functional group in the carboxylic acid Lewis structure. There are many derivatives of the carboxylic acid with variations in the carboxyl group. These are Acid halides, Acid anhydrides, Esters and Amides.

carboxylic acid lewis structure

Many synthetic and natural carboxylic acids have occurred ranging from small molecule acetic acid to complex amino acids or long-chain fatty acids.

Emphasizing more on the carboxylic acid Lewis structure than the carbon and oxygen in the carbonyl group is of sp2 hybridization with trigonal shape. Along with similar lines, the hydroxyl group is also of sp2 hybridization. The bond length of C=O is 1.23 Å and of C-O is 1.36 Å. The bond angle between C=O and C-O is 120°.

Properties described by Carboxylic Acid Lewis Structure

The presence of a double bond in the carboxylic acid Lewis structure is of great significance as it explains the various properties of different compounds of carboxylic acid. The principal properties are:

·        The acidity of Carboxylic acid Lewis structure

·        Solubility of Carboxylic acid Lewis structure

·        The boiling point of Carboxylic acid Lewis structure

The acidity of Carboxylic acid Lewis structure

One of the major properties of carboxylic acid Lewis structure is hidden in its name which is acidity. Carboxylic acid as the name suggests is considered a stronger acid class among organic compounds though it is much weaker than inorganic mineral acids like sulfuric acid (H2SO4), nitric acid (HNO3), and hydrochloric acid (HCl).

The reason behind the increased acidity of carboxylic acid among organic compounds can be easily described when compared with alcohol. Both of them have hydroxyl group (-OH) present in their structural representation. The basic definition of acidity is the donation of hydrogen ions or protons (H+).

In this context alcohol and carboxylic acid form an alkoxide ion (RO) and carboxylate ion (RCOO) respectively. Between these two ions, the carboxylate ion is more stable due to resonance. It has 2 resonating structures which lead to the delocalization of electrons. On the flip side, no resonance is observed in alkoxide ions and there is only a single structure. So this leads to less stability and no delocalization of electrons thereby reducing acidity.

Solubility of Carboxylic acid Lewis structure

Discussing solubility, then less than 5 chains of carboxylic acid Lewis structure are easily soluble in water. The larger or higher molecular weight carboxylic acids are not soluble in an aqueous medium due to the large hydrocarbon part which is considered hydrophobic or water repellent in nature. These high molecular weight carboxylic acids are easily soluble in organic solvents like benzene and toluene.

The boiling point of Carboxylic acid Lewis structure

Carboxylic acid has a high boiling point than its other organic counterparts. Even small molecular weight carboxylic acids like formic acid (HCOOH) have boiling points higher than water. This is because the carboxylic acid Lewis structure has dimer (RCOOH)2 forming tendencies because it can easily form intermolecular hydrogen bonds which are tough to break. So additional heat and extra energy are required to break the hydrogen bonds. That is the reason why maximum carboxylic acids are solids in nature.

Applications of Carboxylic acid Lewis structure

Various carboxylic acids play different roles and have different usages and applications. For instance, methionic acid (HCOOH) is used in leather tanning and as a textile dyeing agent. It is also used as medicine to treat gout or as an antiseptic. It is found useful in the rubber industry as a potential latex coagulating agent.

Ethanoic acid (CH3COOH) or acetic acid is one of the most popular in the carboxylic acid family. It is very commonly used as a solvent in laboratory preparations. It is one of the main ingredients in cosmetic products, perfumes, and dyes. The salts of ethanoic acid are used for medicinal purposes as well. An aqueous solution of ethanoic acid is called vinegar (5-8% by volume). It is used for cooking various kinds of cuisines and delicacies and is the main component of the food industry.

Carboxylic acid Lewis structure (Related FAQs)

What is the difference between aliphatic and aromatic carboxylic acid?

The basic difference is that aliphatic carboxylic acids are open-chain compounds and the aromatic counterparts are closed chains or cyclic structures like rings. But all closed chain structures are not called aromatics. The aromatics one has a particular aroma hence the name. Another major difference is acidity. Aromatic carboxylic acids are more acidic because the benzene ring shows the –I inductive effect and strong hydrogen bonds between molecules which is not observed in the aliphatic ones.

Name the strongest carboxylic acid and the reason behind it.

The strongest carboxylic acid is chloroacetic acid (CCl3COOH). This is because chlorine is very electronegative and can attract electron density towards itself. This weakens the O-H bond thereby making it the strongest acid as compared to other carboxylic acids.

Mention the natural occurrence of carboxylic acid focusing on one example

Carboxylic acids can be easily found in nature. Focusing on one natural carboxylic acid then citric acid is one of them. It is found in citrus fruits like lemons, oranges, Indian gooseberries, etc. It has a high content of vitamin C in it. It is a very large molecule with 3 ionizable hydrogens. It gives a sour taste or a tart-like flavor.

Mansi Sharma

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