Separation Techniques

Separation Techniques• Hand separation

• Filtration

• Extraction

• Fractional distillation

• Chromatography

• Centrifugation

• Evaporation

• Distillation

• Solvent extraction

• Recrystallization

• Gravity separation

Separation Techniques

• Which types of matter can we separate?

• Why?

Filtration

• Separates liquid-solid mixtures• Filter paper: lets liquid through, keeps solids out

• Vacuum filtration: water flow creates vacuum in filter flask and sucks air through the filter paper

Filter Paper

Vacuum Filtration

Chromatography

• Separates liquid-liquid mixtures

• A mixture carried by a solvent through a stationary medium (solid column, filter paper)

• Separation occurs when components of the mixture move through the medium at different speeds

Paper & Thin Layer Chromatography

• Solvent can be a number of things (H2O, ether, ethyl acetate)

• Stationary medium: chromatography paper

Paper & Thin Layer Chromatography

• “Spot” your chromatography paper with your mixture near the bottom

• Put your paper in the container with solvent• Solvent will go up the paper and carry the

mixture up with it• Components will separate if they travel at

different speeds

Paper & Thin Layer Chromatography

Paper & Thin Layer Chromatography

• To identify the components of a mixture, use Rf values

• Rf = distance traveled by component distance traveled by the solvent

• Compare experimental Rf values with reference Rf values to identify your components

Evaporation

• Separates solid-liquid mixtures

• Boil away liquid to leave the solid

• E.g. salt production: evaporate water from seawater to get salt

• Can this method be used for liquid-liquid mixtures?

Evaporation of Sea Water

Evaporation of Sea Water

Distillation

• Separates liquid-liquid mixtures

• Uses different boiling points of liquids

• When would this method not be useful?

Distillation

• Liquid with the lowest boiling point evaporates 1st

• Gas is cooled and collected elsewhere

• Once all of the 1st liquid is collected, repeat for the liquid with the next lowest boiling point

Distillation