Separation of Mixtures

Mixtures may be separated by many different techniques based on differing

physical and/or chemical properties

SortingSimply picking apart the different components

This can be easy and obvious…Sort the laundry into colored and whites!

Or it can be challenging…An organic chemist who used a microscope to sort out mirror image crystals of a compound

SievingUsing screens to sort by size

Sifting flour or sugar… or gold nuggetsor soil

FiltrationParticles separated form liquid or gas

Coffee, Furnace,Lab filter setup with funnel

DecantationPouring liquid off of settled mixture

Or remove a layer of liquid

Wine from sedimentCleaner water in water treatment plant

MagnetismIron from aluminum, plastic, and paperat recycling plant

Cow magnets!

DensityDifferent types of plastic at recycling plant

Oil on water

DissolvingIf one substance dissolves and another doesn’t

Salt and sand…salt dissolves in water…sand doesn’t…sand settles

Tea flavor from tea leaves…flavor and color dissolves…tea leaves don’t…the bag acts as a filter

CentrifugationSpinning to pull heavier part of mixture to bottom

Blood cells are separated from serum

The spin cycle in the washer removes water from clothes

DistillationDifferences in boiling points can be used to separate liquids

(differences in freezing and sublimation points may also be used )

Alcohol in stillsOil refineries

ChromatographyFrom “chroma” meaning color because this technique was first used for dyes

A mobile phase carries sample along over or through a stationary phase.

Components are separated because they have different attractions for the phases.

Paper chromatography to separate pigments in ink is one example

There are many variations for many different mixtures

EvaporationRemove a liquid from a solid

Sea salt isolated by evaporating sea water in shallow ponds

Solids may also be purified by recrystallization

ShakingMotion… a dog shaking to remove water Gravity/density… gentle shaking causes dense items to sink and less dense to rise

As you can see, almost any difference in physical properties can be used to separate mixtures physically

Differences in chemical properties can also be used to separate mixtures chemicallt. For example, oil floats on water (physical difference in density) and burns, but water does not (chemical property of flammability)

This picture shows an oil spill being contained and burned.

SEPARATION TECHNIQUES

are limited only by people’s ingenuity!