AQA GCSE FOUNDATION Chemistry: Alcohols and Carboxylic Acids

AQA GCSE Foundation Chemistry: Alcohols and Carboxylic Acids

1. Introduction

Alcohols and carboxylic acids are two important classes of organic compounds with diverse applications in our everyday lives. They are characterized by the presence of specific functional groups, which determine their chemical properties and uses.

2. Functional Groups

Alcohols:

• Functional group: Hydroxyl group (-OH)
• General formula: R-OH, where R is an alkyl group (a chain of carbon and hydrogen atoms)

Carboxylic acids:

• Functional group: Carboxyl group (-COOH)
• General formula: R-COOH, where R is an alkyl group

3. Properties

Alcohols:

• Solubility: Lower alcohols (like methanol and ethanol) are soluble in water due to hydrogen bonding between the -OH group and water molecules. Solubility decreases as the carbon chain length increases.
• Boiling point: Alcohols have higher boiling points than alkanes with similar molecular masses due to hydrogen bonding.
• Flammability: Alcohols are flammable and burn to produce carbon dioxide and water.

Carboxylic acids:

• Solubility: Similar to alcohols, lower carboxylic acids are soluble in water. Solubility decreases as the carbon chain length increases.
• Boiling point: Carboxylic acids have higher boiling points than alcohols due to stronger hydrogen bonding between molecules.
• Acidity: Carboxylic acids are acidic due to the presence of the carboxyl group, which can donate a proton (H+).
• Odor: Many carboxylic acids have strong, pungent odors.

4. Uses

Alcohols:

• Methanol (CH3OH): Used as a solvent, fuel, and in the production of other chemicals.
• Ethanol (C2H5OH): Found in alcoholic beverages, used as a solvent, biofuel, and in the production of other chemicals.
• Propanol (C3H7OH): Used as a solvent and in the production of plastics.

Carboxylic acids:

• Ethanoic acid (CH3COOH): Commonly known as vinegar, used in food preservation, as a cleaning agent, and in the production of other chemicals.
• Methanoic acid (HCOOH): Used in the textile industry for dyeing and leather tanning.
• Butanoic acid (C3H7COOH): Gives rancid butter its characteristic odor.

5. Reactions

Alcohols:

• Combustion: Alcohols burn in air to produce carbon dioxide and water.
• Oxidation: Primary alcohols can be oxidized to aldehydes and then to carboxylic acids. Secondary alcohols can be oxidized to ketones.

Carboxylic acids:

• Reaction with bases: Carboxylic acids react with bases to form salts and water.
• Esterification: Carboxylic acids react with alcohols to form esters in the presence of an acid catalyst.

6. Summary

Alcohols and carboxylic acids are important classes of organic compounds with diverse uses in our everyday lives. They are characterized by the presence of functional groups - the hydroxyl group in alcohols and the carboxyl group in carboxylic acids. These functional groups determine their chemical properties and reactivity, leading to various applications in different industries.