Acids, Bases, and Salts - SS1 Chemistry Past Questions and Answers - page 5

Neutralisation reactions occur when an acid reacts with a base to produce salt and water. The reaction involves the transfer of protons (H+) from the acid to the hydroxide ions (OH-) from the base, resulting in the formation of water and a salt compound.

 

Applications of Neutralisation Reactions:

-       Antacid: Neutralisation reactions are used to alleviate symptoms of acidity in the stomach. Antacid medications, such as calcium carbonate (CaCO3), react with excess stomach acid to neutralise it.

 

-       Water Treatment: Neutralisation reactions are employed in water treatment processes to adjust the pH of acidic or alkaline water sources. Acidic water is treated with alkaline substances, like sodium hydroxide (NaOH), to neutralise it and make it safe for consumption.

 

-       Agricultural Practices: Neutralisation reactions are utilised in agricultural practices to modify soil pH. Lime (calcium hydroxide, Ca(OH)2) is added to acidic soils to neutralise the acidity and promote healthy plant growth.

 

Formation and Properties of Salts:

During a neutralisation reaction, the combination of the acid and base results in the formation of a salt. Salts are ionic compounds composed of positive ions (cations) derived from the base and negative ions (anions) derived from the acid.

 

Properties of salts include:

-       Ionic Nature: Salts exist as a crystal lattice structure composed of positive and negative ions held together by ionic bonds.

-       Solubility: Salts can be soluble or insoluble in water, depending on their chemical composition. Soluble salts dissociate into ions when dissolved in water, while insoluble salts remain as solid particles.

-       Melting and Boiling Points: Salts generally have high melting and boiling points due to the strong electrostatic forces between ions.

-       Conductivity: When dissolved in water or molten state, salts can conduct electricity as they dissociate into ions that can move and carry electric charge.

-       Colour and Taste: Salts can exhibit various colours, and their taste depends on the specific ions present. For example, sodium chloride (NaCl) is white and tastes salty.