This Matter Around Us is Pure

Definition of Pure Substances

• Pure Substance: Substances that consist of only one type of particles (atoms or molecules).
• Examples:
  • Copper - made up of only copper atoms.
  • Water (H2O) - made up of only H2O molecules.

Impure Substances

• Impure Substances: Substances that are made up of different types of particles.
• Examples:
  • Adding salt to water makes the water impure.
  • Impure substances are also known as mixtures.

Types of Pure Substances

• Elements: Made up of only one type of atoms. (Examples: Copper, Iron, Oxygen)
• Compounds: Made by combining two or more types of atoms in a fixed ratio. (Examples: Water, Carbon Dioxide - CO2)

Mixture

• Mixture: A combination of two or more substances which may be uniformly or non-uniformly mixed.

  Types:

  • Homogeneous Mixture: In which all components are uniformly mixed. (Examples: Sugar and water)
  • Heterogeneous Mixture: In which all components are not uniformly mixed. (Examples: Water and oil)

Solution

• Example of a homogeneous mixture: Such as lemonade, sugar solution.

• Solute: The substance that dissolves.

• Solvent: The substance in which others dissolve.

  Properties:

  • Particles are very small, cannot be seen with the naked eye.
  • Does not scatter light.
  • Solvent and solute cannot be separated by filtration.
  • As temperature increases, the solubility of the solute also increases.

Saturated and Unsaturated Solutions

• Unsaturated Solution: More solute can be dissolved.
• Saturated Solution: No more solute can be dissolved.

Concentration

• Two ways to calculate the concentration of a solution:
  • Mass by Mass percentage: [\text{Mass percentage} = \frac{\text{Mass of Solute}}{\text{Mass of Solution}} \times 100]
  • Mass by Volume percentage: [\text{Mass by Volume percentage} = \frac{\text{Mass of Solute}}{\text{Volume of Solution}} \times 100]

Colloidal and Suspension Solutions

• Colloidal Solutions: Contain small particles that do not settle. Example: Milk.
• Suspensions: Contain larger particles that settle over time. Example: Muddy water.

Tyndall Effect

• Scattering of light making the path of light visible.
• Solution: Does not show Tyndall effect.
• Colloidal Solution: Shows Tyndall effect.
• Suspension: Shows Tyndall effect.

Summary

• Concept of pure substances and impure substances.
• Types of mixtures and their properties.
• Properties and differences between solution, colloidal solutions, and suspension.
• Tyndall effect and its importance.

In the next part, we will study more aspects of this chapter.