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Matter - Honors Chemistry - Chapter 3

CHEMISTRY IS THE STUDY OF MATTER AND THE CHANGES IT UNDERGOES

DEFINITION OF MATTER

  • Matter is anything that possesses mass and volume.
    • Examples of Matter:
    • Air
    • Glass
    • Cotton
    • Water
    • Nylon

Mass vs. Volume

  • Mass:
    • Definition: The amount of matter the object contains.
    • Unit: Kilograms (kg)
  • Volume:
    • Definition: How much space an object takes up.

STATES OF MATTER

  • Solid:
    • Fixed shape and fixed volume.
  • Liquid:
    • Variable shape, fixed volume.
  • Gas:
    • Variable shape and variable volume.
  • Plasma:
    • Ionized gas at high temperatures.

PHYSICAL CHANGES AND CHEMICAL CHANGES

Physical Changes

  • Definition: Changes that do not alter the composition of a substance.
    • Indicators of physical changes:
    • Change in size
    • Change in shape
    • Change in form
    • Change in state (e.g., solid to liquid)
  • Examples of Physical Properties:
    • Density
    • Hardness
    • Texture

Chemical Changes

  • Definition: Changes that result in the formation of new substances.
    • Indicators of chemical changes:
    • Color change
    • Formation of a precipitate
    • Gas released
    • Heat released or absorbed
    • Light emitted

CLASSIFICATION OF MATTER

Categories of Matter

  • Pure Substance:

    • Definitions: Have constant composition and are uniform throughout the sample. Only one substance is present.
    • Examples:
    • Copper (Element)
    • Calcium Carbonate (Compound)

  • Mixture:

    • Definition: Have variable composition and may or may not be uniform throughout the sample.
    • A physical combination of two or more substances.
    • Examples:
    • Gatorade (Homogeneous)
    • Oil and Water (Heterogeneous)

Pure Substances vs. Mixtures

Three Major Differences:

  1. Composition: Mixtures have variable composition, whereas pure substances have fixed composition.
  2. Properties: The properties of the components in a mixture are observable because there are no bonds between the components.
  3. Separation Methods: Components of a mixture can be separated by physical means, while compounds can only be separated by chemical means.

SEPARATION OF MATTER

Methods for Separation:

  1. Electrolysis:

    • Used to separate compounds into their elements:
      • Example: Water can be separated into hydrogen and oxygen gas using electrolysis.

  2. Filtration:

    • Technique used to separate a solid from a liquid based on differences in particle size.
    • Example of Filtration Setup:
      • Uses a funnel and filter paper.
      • Liquid (filtrate) passes through the filter leaving the solid behind.

  3. Crystallization:

    • Based on differences in solubility.
    • An impure solid is dissolved in a hot solvent; upon cooling, the purified solid crystallizes out.

  4. Distillation:

    • Based on differences in volatility:
      • A mixture of liquids is heated until the substance with the lowest boiling point vaporizes.
      • The vapor is then cooled to condense into liquid (distillate).

  5. Chromatography:

    • Based on differences in affinity between substances:
      • The mixture is captured between a stationary phase and a mobile phase, allowing separation based on the level of attraction.

  6. Extraction:

    • Based on differences in solubility between a substrate and its matrix.
    • Polar substances dissolve in polar solvents and can be treated chemically for separation into layers, which are filtered out using a separatory funnel.

PHASE CHANGES

  • Endothermic Changes: More ordered to less ordered state
    • Solid to Liquid: Fusion/Melting/Liquefaction
    • Liquid to Gas: Vaporization
    • Solid to Gas: Sublimation
  • Exothermic Changes: Less ordered to more ordered state
    • Liquid to Solid: Crystallization
    • Gas to Liquid: Condensation
    • Gas to Solid: Deposition

NATURE OF PROPERTIES

Types of Properties:

  1. Intensive Properties:
    • Definition: Properties that do not depend on the amount of substance present.
      • Examples:
      • Density
      • Melting Point
      • Boiling Point
  2. Extensive Properties:
    • Definition: Properties that depend on the amount of substance present.
      • Examples:
      • Mass
      • Volume
      • Time