Lesson 1.7: Substances vs. Mixtures

In this lesson, we explore the fundamental difference between pure substances and mixtures, focusing on how chemists classify matter based on composition and physical properties.

You’ll learn how to:
• Distinguish between substances and mixtures
• Compare homogeneous and heterogeneous mixtures
• Understand why mixtures have variable composition
• Explain how mixtures can be separated using physical processes

Several separation techniques are introduced and demonstrated, including:
• Filtration
• Distillation
• Crystallization
• Chromatography

Throughout the lesson, we emphasize an important theme in chemistry:
👉 Physical changes and physical separations do not alter chemical identity.

This video is part of Unit 1: Properties of Matter and builds the foundation for later topics such as phase changes, solutions, and chemical reactions.

Recommended prior knowledge:
✔ Metric system review
✔ Accuracy vs. precision
✔ Physical vs. chemical properties