Everyday consumer products

Question 1

State the uses of alcohols

Answer 1

Fuels
Alcohols, such as ethanol, are commonly used as fuels because they are highly flammable and burn with a clean flame, which makes them environmentally friendly when compared to fossil fuels. They can be used alone or blended with petrol to reduce emissions.

Solvents
Alcohols, like methanol and ethanol, are also effective solvents. They can dissolve substances that may not be soluble in water. This makes them useful in products such as paints, perfumes, and pharmaceuticals, where they help dissolve ingredients that might not mix well otherwise.

Question 2

Describe the properties of alcohols

Answer 2

Solubility
Smaller alcohols (with up to 4 carbon atoms) are soluble in water.
Solubility decreases with alcohols containing more than 4 carbon atoms due to the increasing size of the molecule.

Melting and Boiling Points
As the size of the alcohol molecule increases, the melting and boiling points increase.
This is due to the increasing strength of intermolecular forces, which require more energy to overcome.

Question 3

Name and recognise the functional group in alcohols

Answer 3

The functional group in alcohols is called the hydroxyl group and is represented by -OH.

Exam Tip
Pay attention to whether a question asks you to name the functional group or to identify it. Naming requires stating ‘hydroxyl group’ while identifying involves recognizing -OH.

Question 4

State the uses of carboxylic acids

Answer 4

Preservatives
Carboxylic acids like are used as food preservatives. They help prevent the growth of bacteria and fungi, extending the shelf life of food products.

Soaps and Detergents
Carboxylic acids are used in the production of soaps. Long-chain carboxylic acids (fatty acids) are reacted with bases to create soap, which is used for cleaning.

Question 5

Describe the properties of carboxylic acids

Answer 5

Solubility
Small carboxylic acids (up to 4 carbon atoms) are miscible (soluble) in water.
Larger carboxylic acids (with more than 4 carbon atoms) are generally insoluble in water due to the increasing size of the molecule.

Melting and Boiling Points
As the size of the carboxylic acid molecule increases, the melting and boiling points also increase.
This is due to the increasing strength of intermolecular forces, which require more energy to overcome.

Acidic Nature
Solutions of carboxylic acids have a pH less than 7.
Like other acids, carboxylic acids react with metals, metal oxides, hydroxides, and carbonates, forming salts.

Question 6

Name and recognise the functional group in carboxylic acids

Answer 6

The functional group in carboxylic acids is called the carboxyl group and is represented by -COOH.