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The Physical Separation of Substances Filtration • Distillation Hand Separation • Evaporation Solvent Extraction • Recrystallization Gravity Separation • Paper Chromatography By: Allan Y, Pauline W, Alex W, and Justus S Filtration Allows for the separation of liquids from solids Usually involves a liquid (filtrate) that is passed through a filter; the material that remains on the filter is called the residue Filtration Filtration cannot be used to separate dissolved solids from a liquid (filtration only works when the solid particles are big enough to be seen) Distillation As a liquid with the lowest boiling temperature in the solution boils first, the vapor produced ascends to the top of the distillation flask, passes a thermometer, and enters the side-arm of the flask which leads to the condenser. As the vapor enters the cold inner surface of the condenser, the gas cools and condenses back into a liquid, which drips out the end of the condenser as the distillate Hand Separation Separation of MECHANICAL MIXTURES Can often be separated by HAND or by use of SIEVE or MAGNET Evaporation Separation of SOLID-IN-LIQUID SOLUTIONS Can often be separated by allowing liquid to EVAPORATE or to be BOILED AWAY, leaving solid SOLVENT EXTRACTION There are two ways in which this technique can be used … # 1… Extraction of a solid from a mechanical mixture This method requires a liquid that dissolves one or more solids present so the desired product is left behind or dissolved and separated by evaporation #2 … Extraction of a dissolved liquid or solid from a liquid solution To carry out this technique, a solution with one or more solid and/or liquid substances dissolved in a liquid solution, a solvent must contain two properties: The added solvent is immiscible with the solvent present The added solvent dissolves one or more desired substances from the substances and leaves behind the unwanted After the solvent is added, the mixture is mixed in a separatory funnel and the added solvent is drained from the original solvent RECRYSTYALLIZATION Recrystallization is a variation of evaporation in which a solid in a solid-in- liquid solution is separated in a pure crystalline state A saturated solution must be prepared in order for recrystallization to occur A solid is added to a solvent until no more solid can dissolve and adding just enough hot solvent to dissolve the solid, the mixture is allowed to cool and evaporate, forming crystals Once the crystals have formed, they are removed by either hand separation or filtration Gravity Separation Separation of two components of a homogeneous mixture Clarification and thickening are two different products from the same method Method: in a mix of a solid and liquid, the solid will gradually gather at the bottom of the container while the liquid remains on top Gravity Separation Clarification wishes the purified liquid at the end Thickening wishes the purified solid at the end When feasible, centrifugal force may also be used in place of gravity (faster separation due to higher pressure upon contents) Paper Chromatography Separates small amounts of Solid-in-Liquid solutions containing two or more dissolved solids It requires a drop of the mixture placed near the end of a sheet of absorbent paper That end is dipped in the “developing” mixture Paper Chromatography As the solvent gradually travels up the sheet it will carry along the dissolved solids The edge of the solvent’s travels is known as the “solvent front” Depending on how readily the solids are dissolved by the solvent, various streaks of color will appear behind the solvent front The END!!!!!!!!
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