Physical Properties - Chemistry Part I

Physical Properties

Definition of Physical Properties

  • A physical property is a characteristic of a substance that can be determined without changing the composition of that substance (composition does not change).

  • These properties can be observed directly using:

    • Five senses

    • Measuring instruments

  • Physical properties may be classified as either:

    • Qualitative, such as colour or texture

    • Quantitative, such as mass and length

Qualitative Physical Properties

List of Qualitative Properties

  • Lustre: Refers to the shininess or dullness of a substance.

  • Optical Clarity: The ability of a substance to allow light to pass through it.

  • Brittleness: The quality of a material to break easily, indicating low flexibility.

  • Viscosity: Refers to the ability of a substance to flow or pour readily.

  • Hardness: The relative ability of a substance to scratch or be scratched by another substance.

  • Malleability: The ability of a substance to be hammered into a thinner sheet or molded into different shapes.

  • Ductility: The ability of a substance to be drawn (pulled) into a thinner strand, such as wires.

  • Electrical Conductivity: The capability of a substance to allow an electric current to pass through it.

Examples of Physical Properties

Lustre

  • Rusty Nails: Exhibit low lustre, appearing dull.

  • Shiny Kettle: Demonstrates high lustre, reflecting light effectively.

Malleability and Brittleness

  • Silver: Noted for its malleability, allowing it to be easily molded into different shapes.

  • Glass: Characterized as brittle; it can easily break under stress.

Viscosity

  • Syrup: Identified as viscous due to its thick consistency, resisting flow.

  • Water: Exhibits lower viscosity, flowing more readily.

Physical Changes

  • A physical change is a change where the composition of the substance remains unaltered and no new substances are produced.

Examples of Physical Changes

  • Folding a Piece of Paper: Transforming it into an airplane alters its size or shape but not its composition.

  • Melting Ice: A change of state from solid to liquid while maintaining the water's chemical identity.

  • Mixing Sugar into Coffee: A process described as dissolving, where sugar's properties change due to solution but its composition remains the same.

Homework Assignment

  • Read pages 179-182 in the textbook.

  • Complete problems #1 - 5 on page 182.