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Chapter 4 Exploring Diversity Of Matter Using Separation Techniques -…
Chapter 4
Exploring Diversity Of Matter Using Separation Techniques
Magnetic attraction
Used to separate magnetic materials from non-magnetic materials.
Makes use of the fact that only some materials are attracted to magnets.
We can use this property to separate these metals from mixtures.
Iron
Nickel
Cobalt
Steel
Applications
Salvaging of iron and steel.
Food processing.
Separating a mixture of sulfur and iron filings.
Filtration
The technique used to separate an insoluble solid from the liquid in a solid-liquid mixture.
Works on the basis that, in a suspension, the insoluble solids are larger ( in size ) than liquid particles.
Used to separate insoluble solids from a suspension.
Applications
Coffee makers
Water treatment plants
Evaporation
The technique used to separate dissolved solids from a solid-liquid mixtures.
Makes use of the fact that the solvent in a solution can vaporise at any temperature, leaving behind a residue of the solid that was dissolved in the liquid.
Applications
Used to obtain salt from saltwater etc.
Simple distillation
The technique used to separate a pure liquid from a solid-liquid or liquid-liquid mixture.
Involves vaporisation ( boiling ) and condensation.
Works on the basis that when a liquid evaporates from a solution, it will condense to form a pure liquid.
Applications
Paper chromatography
The technique used to separate small amounts of substances, especially pigments from mixtures.
Makes use of the fact that different substances dissolve to different extents in a mixture.
Different substances move at different rates up the chromatography paper.
Substances that are more soluble in a solvent will move faster than substances that are less soluble.
Applications
Identifying the contents of a mixture.
Identifying food colourings: paper chromatography can be used to ensure that harmful colourings are not used in food.
Identifying the dyes used in ink: paper chromatography can be used to find out the different kinds of dyes that make up different inks ( in cases where we need to identify forged written documents.
Test the purity of a substance.
Desalination
Removes dissolved salts from seawater to obtain pure water.
Distillation is a technique used to carry out desalination . It is not widely used as it is expensive and needs a lot of heat energy.
Seawater is heated in a boiling chamber to produce steam. The steam condenses as it passes through a condenser. Water is then collected as a distillate.
Desalination plants are used to convert seawater to drinking water on ships and in many dry regions on the earth.
Microfiltration
Removes small particles from the treated sewage water.
A membrane filter ( with many tiny pores) traps suspended solids and most disease-causing micro-organisms.
Water obtained from microfiltration contains mainly dissolved salts and chemical molecules
The water obtained from microfiltration is pumped at high pressures through a special membrane.
The pores of the membrane is so small that only very small molecules, such as water molecules, can pass through, but not disease-causing micro-organisms, dissolved salts and chemical molecules.
Reverse osmosis
This technique removes disease causing micro-organisms , dissolved salts and chemical molecules from sewage water.
The water obtained from reverse osmosis is free from bacteria and viruses. It also contains trace amounts of dissolved salts and chemicals.