📘 The Amazing World of Solutes, Solvents, and Solutions
Class: 8 | Subject: Science
🔹 1. What is a Mixture?
A mixture is formed when two or more substances are mixed together.
- Uniform mixture: Looks same everywhere (salt + water)
- Non-uniform mixture: Looks different (sand + water)
🔹 2. Solution, Solute & Solvent
- Solution: Uniform mixture
- Solute: Substance that dissolves (salt)
- Solvent: Substance that dissolves solute (water)
🔹 3. Saturated & Unsaturated Solutions
- Unsaturated: Can dissolve more solute
- Saturated: Cannot dissolve more solute
🔹 4. Solubility & Temperature
- Solids dissolve more in hot water
- Gases dissolve more in cold water
🔹 5. Density & Floating
Density = Mass ÷ Volume
- Higher density → sinks
- Lower density → floats
🧪 Activity Zone
- Add salt to water until it stops dissolving.
- Put an egg in water → then add salt.
- Compare sugar dissolving in hot vs cold water.
📝 Revision Notes – Quick Exam Prep
🔹 Important Definitions
- Solution: Uniform mixture of solute and solvent
- Solute: Substance that dissolves
- Solvent: Substance that dissolves solute
- Saturated solution: Cannot dissolve more solute
- Unsaturated solution: Can dissolve more solute
- Solubility: Maximum solute dissolved at a given temperature
- Density: Mass per unit volume
🔹 Important Formula
Density = Mass ÷ Volume
🔹 Key Points to Remember
- Hot water dissolves more solids
- Cold water dissolves more gases
- Oil floats on water due to lower density
- Ice floats because density of ice < water
- Read water level at bottom of meniscus
🔹 Very Important Questions
- Define solubility.
- Why does ice float on water?
- Differentiate between saturated and unsaturated solution.
- Why do fish need cold water?
- What is density?