Chemistry - Elements, Compounds and Mixtures (Separation Techniques)

An Element is a pure substance made up of only one type of atom and cannot be broken down into simpler substances by chemical means (e.g., Iron ($Fe$), Oxygen ($O_2$)).

A Compound consists of two or more elements chemically combined in a fixed ratio by mass (e.g., Water ($H_2O$), Sodium Chloride ($NaCl$)).

A Mixture contains two or more substances physically mixed in any proportion, retaining their individual properties.

Filtration is used to separate an insoluble solid from a liquid (e.g., sand from water).

Evaporation involves heating a solution to remove the solvent, leaving the soluble solid behind (e.g., obtaining salt from a $NaCl$ solution).

Crystallization is the process of obtaining pure crystals of a soluble substance from its hot saturated solution (e.g., $CuSO_4 \cdot 5H_2O$).

Sublimation is used to separate a mixture where one component changes directly from solid to gas on heating (e.g., Ammonium Chloride ($NH_4Cl$), Iodine ($I_2$), or Naphthalene).

Distillation is used for separating miscible liquids with a large difference in boiling points (typically $> 25^{\circ}C$).

Fractional Distillation is used when boiling points of miscible liquids are very close (e.g., separating components of air or petroleum).

Separating Funnel is used to separate two immiscible liquids based on their density (e.g., oil and $H_2O$).

Magnetic Separation is used when one component of the mixture has magnetic properties (e.g., Iron filings from Sulphur powder).