Notes on Compound and Mixture, and Washing Soda

(a) Compound and Mixture

Compound:

• A compound is a substance formed when two or more elements chemically combine.
• Example: Water (H₂O) is a compound made of hydrogen and oxygen.

Characteristics of Compounds:

• Fixed composition: The elements are present in a specific ratio.
• Unique properties: The compound has different properties than the individual elements.

Mixture:

• A mixture is a combination of two or more substances that are not chemically bonded.
• Example: Air is a mixture of gases like nitrogen, oxygen, and carbon dioxide.

Characteristics of Mixtures:

• Variable composition: The components can be present in any ratio.
• Retain properties: The individual substances keep their original properties.

(b) Washing Soda

Definition:

• Washing soda, also known as sodium carbonate, has the chemical formula Na₂CO₃·10H₂O.

Preparation:

• Washing soda is produced through the Solvay process, which involves:
  1. Reacting sodium chloride, ammonia, and carbon dioxide in water.
  2. Forming sodium bicarbonate, which is then heated to produce sodium carbonate.

Uses of Washing Soda:

• Cleaning Agent: Effectively removes burnt-on grease from kitchen utensils.
• Industrial Applications: Used in soap, glass, and paper manufacturing.
• Water Softening: Helps in removing permanent hardness from water.

Washing soda is a versatile and important chemical in both domestic and industrial settings.