Mixtures and Pure Substances: Properties and Separation

Posted on Nov 27, 2024 in Chemistry

Mixtures and Pure Substances

Definitions

  • Homogeneous Mixture: A mixture with components so small they appear uniform to the naked eye. Aqueous solutions are examples of homogeneous mixtures.
  • Heterogeneous Mixture: A mixture where the components are visible, either with the naked eye or optical instruments.
  • Mixture: Composed of two or more components with undefined proportions.
  • Pure Substance: Matter with a definite and constant composition and distinct properties.
  • Solution: A homogeneous mixture of two or more substances, typically a solute dissolved in a solvent.

Properties

  • Density: The mass of a substance occupying a certain volume.
  • Melting Point: The temperature at which a solid turns into a liquid. For pure substances, the temperature remains constant during the change of state.
  • Boiling Point: The temperature at which a liquid turns into a gas. For pure substances, the temperature remains constant during the change of state.
  • Solubility: The maximum amount of solute that can dissolve in a given amount of solvent.
  • Immiscible: Substances that do not mix.
  • Solubility Curve: A graphical representation of solubility.

Separation Techniques

  • Decanting: Separating a solid from a liquid by pouring off the liquid, leaving the solid behind.
  • Liquid Decantation: Separating immiscible liquids by carefully pouring or using a separating funnel.
  • Filtration: Separating a solid suspended in a liquid by passing the mixture through a filter.
  • Vaporization: Heating a solution to evaporate the solvent, leaving the solid behind.
  • Crystallization: Allowing a solution to evaporate slowly, forming crystals of the solute.
  • Extraction with a Solvent: Separating a component from a mixture by dissolving it in a solvent in which the other components are insoluble.
  • Sublimation: Heating a solid that directly transforms into a gas, which can then be collected and cooled to reform the solid.
  • Magnetism: Using a magnet to separate magnetic substances from non-magnetic ones.
  • Distillation: Separating and recovering liquids from a solution by heating and condensing the vapors.
  • Chromatography: Separating components of a mixture based on their different rates of movement through a stationary phase carried by a mobile phase.