Pure Substances

📚 Key Concepts

🔹 What is a Pure Substance?

A pure substance is a kind of matter that cannot be separated into other kinds of matter by any physical process. It consists of the same type of particles throughout.

Characteristics:

• Same type of particles throughout
• Fixed composition
• Cannot be separated by physical methods
• Definite melting and boiling points

🔹 Difference: Common Usage vs Scientific Usage

Common Usage:

• ‘Pure’ means unadulterated
• Free from harmful additions
• Good quality product

Scientific Usage:

• Contains only one type of substance
• No other substances present
• Made of identical particles

🔹 Examples and Classification

Pure Substances:

• Water (H₂O)
• Carbon dioxide (CO₂)
• Iron (Fe)
• Oxygen (O₂)
• Sugar (C₁₂H₂₂O₁₁)

Not Pure Substances (Mixtures):

• Milk (contains water, proteins, fats)
• Air (mixture of gases)
• Soil (mixture of organic and inorganic matter)
• Fruit juice (contains water, sugars, acids)