Sodium carbonate is a basic salt because it is salt derived from:

(A) strong acid and strong base

(B) strong acid and weak base

(C) weak acid and strong base

(D) weak acid and weak base

Sodium carbonate, commonly known as soda ash or washing soda, is classified as a basic salt. To understand why, we need to look at the components that form sodium carbonate and the nature of the acids and bases involved in its formation.

Breaking Down Sodium Carbonate

Sodium carbonate (Na2CO3) is produced from the reaction between sodium hydroxide (a strong base) and carbonic acid (a weak acid). This reaction can be summarized as follows:

• Sodium hydroxide (NaOH) is a strong base.
• Carbonic acid (H2CO3) is a weak acid.

Understanding the Components

When a strong base reacts with a weak acid, the resulting salt tends to have basic properties. This is because the conjugate base of the weak acid remains in solution and can accept protons (H+ ions), leading to an increase in pH. In the case of sodium carbonate:

• The sodium ion (Na+) does not affect the acidity or basicity of the solution significantly.
• The carbonate ion (CO3^2-) can react with water to produce hydroxide ions (OH-), which increases the basicity of the solution.

Why Sodium Carbonate is a Basic Salt

To summarize, sodium carbonate is a basic salt because it is formed from a strong base (sodium hydroxide) and a weak acid (carbonic acid). This combination results in a salt that, when dissolved in water, increases the pH of the solution, making it basic.

Choosing the Correct Answer

Given the options:

• (A) strong acid and strong base
• (B) strong acid and weak base
• (C) weak acid and strong base
• (D) weak acid and weak base

The correct answer is (C) weak acid and strong base. This aligns with our explanation that sodium carbonate is derived from the reaction of a strong base (sodium hydroxide) and a weak acid (carbonic acid), resulting in a basic salt.

Real-World Applications

Sodium carbonate is widely used in various industries, including:

• Glass manufacturing
• Water softening
• Cleaning agents

Its basic nature makes it effective in neutralizing acids and in processes where pH control is essential.