Chemistry Mixture Separation Methods and Definitions

Fundamental Concepts of Mixtures

Heterogeneous Mixtures

Do not present a uniform appearance to the naked eye. Their components are visibly distinct.

Homogeneous Mixtures (Solutions)

Present a uniform appearance to the naked eye. Their components are indistinguishable, even with a microscope.

Colloids

Mixtures that appear uniform to the naked eye but whose components can be distinguished with a microscope.

Dissolution (Solution Formation)

The process of forming a homogeneous mixture where a major component (the solvent) dissolves one or more other substances (the solutes).

Concentration

A measure indicating the amount of solute dissolved in a given quantity of solvent or solution.

Solubility

The maximum quantity of a substance (solute) that can be dissolved in a determined quantity of solvent at a specific temperature.

Separation Techniques for Mixtures

Techniques for Heterogeneous Mixtures

• Decantation

  Based on the difference in density between the components of a mixture. Used for separating insoluble solids from liquids, and immiscible liquids from each other.

• Sieving (Tamisatge)

  Consists of separating solid particles of different sizes using a sieve.

• Filtration

  Used to separate insoluble solids from a liquid. The mixture is passed through a filter medium (e.g., filter paper) which retains the solid particles while the liquid passes through.

• Centrifugation

  Similar to decantation but accelerated. The mixture is spun at high speed in a centrifuge, causing denser particles to settle rapidly at the bottom.

• Sublimation

  A process where a solid changes directly into a gas without passing through a liquid phase. This can be used to separate a sublimable solid from non-sublimable components by heating and then cooling the gas to re-solidify it.

Techniques for Homogeneous Mixtures

• Evaporation

  Consists of heating a mixture to remove the solvent, leaving the dissolved solid behind. Solid impurities may also remain.

• Crystallization

  Used to separate a dissolved solid from a solvent and obtain it in a pure, crystalline form. The solution is typically heated to concentrate it, then cooled slowly to allow crystals to form.

• Distillation

  Used to separate liquids from a homogeneous mixture based on differences in their boiling points. The liquid with the lower boiling point vaporizes first, is then condensed, and collected separately.

• Extraction (Liquid-Liquid Extraction)

  Used to separate components from homogeneous liquid mixtures, or dissolved solids/miscible liquids that cannot be separated by distillation. It relies on the differential solubility of components between two immiscible liquid phases.

• Chromatography

  Based on the difference in mobility of components as they are carried by a mobile phase (solvent) through a stationary phase (porous medium). Components separate based on their differential affinities for the stationary and mobile phases, resulting in different travel distances.