Test: Alkanoic Acid - JAMB MCQ

Alkanoic acids are characterized by the presence of a carboxyl functional group (-COOH). This functional group consists of a carbonyl group (C=O) and a hydroxyl group (-OH) attached to the same carbon atom. It imparts acidic properties to these compounds and is responsible for their distinct chemical and physical properties.

Ethanoic acid, also known as acetic acid, is an example of a monocarboxylic acid. It has a single carboxyl functional group and is commonly found in vinegar. Succinic acid, citric acid, and phthalic acid are examples of dicarboxylic acids as they contain two carboxyl groups.

The IUPAC name for CH₃CH₂COOH is propanoic acid. It consists of three carbon atoms, hence the prefix "prop-", and has a carboxyl group attached to the second carbon atom.

Neutralization reactions involve the combination of an acid and a base to form a salt and water. When an alkanoic acid reacts with a base, such as sodium hydroxide (NaOH), it forms the corresponding salt (e.g., sodium ethanoate) and water.

Ethanoic acid (acetic acid) is commonly used in the preparation of esters. It readily undergoes esterification reactions with alcohols in the presence of an acid catalyst, producing esters and water.

Butanoic acid has the chemical formula C₄H₈O₂. It consists of four carbon atoms, eight hydrogen atoms, and two oxygen atoms. The presence of the carboxyl group (-COOH) gives it acidic properties.

Benzoic acid is an example of an aromatic acid. It contains a benzene ring (aromatic ring) with a carboxyl group (-COOH) attached to it. The presence of the benzene ring contributes to its unique chemical and physical properties.

The reaction between ethanol (CH₃CH₂OH) and ethanoic acid (CH₃COOH) in the presence of an acid catalyst results in the formation of ethyl ethanoate (CH₃CH₂COOC₂H₅), an ester, and water (H₂O). The -OH group of ethanol reacts with the carboxyl group (-COOH) of ethanoic acid, forming an ester linkage.

In the neutralization reaction between ethanoic acid and sodium hydroxide, the byproduct is sodium ethanoate (sodium acetate), which is a salt. The reaction can be represented as follows:
CH₃COOH + NaOH → CH₃COONa + H₂O

Generally, the acidity of alkanoic acids decreases with an increase in the carbon chain length. This is due to the decreasing polarity and increasing hydrophobic nature of the alkyl group attached to the carboxyl group. As the carbon chain length increases, the alkyl group dominates the electron-donating nature, making it less favorable for the release of protons (H+ ions) and thus reducing the acidity.