Chem Separation Techniques Inv

Study or Fail

Separation Techniques can be separated by…

Physical or chemical properties

Physical properties are…

characteristics of a substance that can be observed or measured without changing the identity of the substance

Chemical properties are…

the ability of a substance to undergo a specific chemical change

Materials are…

substances which are used to make objects, and are often mixtures of many substances

Elements are…

pure substances made up of only one type of atom, and found on periodic table

Compounds are,,,

pure substances made up of more than one type of atom chemically bonded together in fixed ratios

Mixtures are…

a combination of different elements and/or compounds, with not all atoms chemically bonded together, do not have fixed ratios, and can be separated by physical means.

They also have properties that can change depending on proportion of each component in mixture

Pure substances are…

definite → have specific physical properties that are unchangeable

Types of separation techniques…

Sieving

Filtration

Sedimentation AND decantation

Separating funnel

Distillation

Evaporation

Fractional distillation

Centrifugation

Chromatography

Magnetic separation

Sieving

• large particles can’t fit through small holes, but fine particles can

• relevant PHYSICAL property - particle size

Filtration

• filtrate is collected in flask as particle size is small enough to fit through pores in filter paper

• residue can’t pass through filter paper due to larger particle size

• relative PHYSICAL property - particle size

Sedimentation and decantation

• sedimentation → allows sediments to settle at bottom of beaker

• decantation → use stirring rod to lead less dense liquid layer (SUPERNATANT) along it into collection flask, leaving dense substance in og beaker (SEDIMENT/PRECIPITATE)

• relative PHYSICAL property - density

Separating funnel

• for 2 liquids at different densities

• top layer will be LESS DENSE than bottom layer (bc more denser substance will have more part. so more heavier)

• denser substance will be collected in collection flask

• relative PHYSICAL property - density

Evaporation

• substance with lower b.p. will evap. before other

• sometimes substance with higher b.p. can crystallise

• relative PHYSICAL property - boiling point

Distillation

• substance with lower b.p. evaporates, enters another condenser where cold water runs on surface, thus cooling evaporated substance (DISTILLATE) back into liquid, then collected in receiving flask

• condenser has tube going in with cold water, then going out into sink for constant cool

• thermometer in round flask (o.g. flask) used to ensure only distillate is being evaporated (to know which one is evaporating)

• relative PHYSICAL property - boiling point

Fractional distillation

• between fuels

• all fuels are heated into gas, them pumped into fractioning column

• Column is cooler, so gases turn into liquid, but rise higher and higher first, to designated level

• gases turn into liquids → if liquids fall down to lower layers, become gas since too hot and go back up

• all layers continuously pumped to outside, so no space for liquid to overflow levels

• relative PHYSICAL property - boiling point

Centrifugation

• mixture is rapidly spun around

• components separated → less dense are higher, denser are lower

• relative PHYSICAL property - density

Chromatography

• substance on chromatography paper has components that have different polarity (measure of how unevenly electrical charges are distributed across a molecule), so components electrical charges attract differently to substance, thus moving at different speeds along chrom paper ( since they can be attracted to paper, which has electrical charge → attracting polar substances)

• non-polar substances don’t get attracted to paper and move quickly with liquid

• relative CHEMICAL property

Magnetic separation

• separates components by magnetic properties

• MAGNETIC METALS - IRON, COBALT, NICKEL

• relative PHYSICAL property - magnetism

Accuracy

• Closeness of agreement between measured value and true/accepted value

• Linked to random errors

• more random errors → lower accuracy

Precision

• Degree of exactness of a measurement

• Linked to systematic errors