Chemistry Methods of Separation

Distillation

Distillation

Seperating mixtures that have liquids

Simple distillation is used to…

Separate a liquid from a solution

Step one of simple distillation

Heat up the mixture so the liquid you want evaporates

Step two of simple distillation

The liquid rises up and pressure forces it down the condenser

Step 2.5 of simple distillation

The vapour cools because of the water jacket and condenses into a liquid form

Step three of simple distillation

The liquid runs down the pipe and is collected in the beaker

Fractional distillation is used to

Separate mixtures of liquids

Step one of fractional distillation

Heat up the mixture

Step two of fractional distillation

The mixture with the lowest boiling point evaporates first, condenses into liquid and is collected in the beaker

Step three of fractional distillation

The other substances will rise up too, but the glass rods are cooler than their boiling point so they condense back into liquids

Step four of fractional distillation

Raise the temperature and do the same for the other substances in the mixture

Mixture

A mixture of a liquid and insoluble solid

Solution

Mixture of a liquid and soluble solid

Solute

A substance dissolved into a solution

Solvent

The liquid the solute is dissolved into

Filtration

Separates insoluble solids from liquids

How does filtration work?

The filter paper has tiny holes in it that water can get through, but the solid is too big and is left behind on the paper

Step one of evaporation

Put the solution into a crucible and place it on a tripod

Step two of evaporation

Heat the solution with a Bunsen burner

Step three of evaporation

The solvent evaporates and the solution becomes more concentrated

Step 3.5 of evaporation

Crystals begin to form and eventually the solvent evaporates completely, leaving behind crystals of the solution

Advantage of evaporation

It’s quick and easy

Disadvantage of evaporation

Some solids decompose when heated

Step one of crystallisation

Place the solution in a water bath

Step two of crystallisation

When crystals begin to form stop heating it and leave it to cool

Step three of crystallisation

As it cools more more crystals will form as solids are less soluble at colder temperatures

Step four of crystallisation

Filter out the crystals from the remaining solution and dry the crystals on filter paper

Chromatography

Used to separate the different substances in a mixture

Paper chromatography…

Separates the different dyes in an ink

Step one of paper chromatography

Take a piece of paper and draw a line at the bottom called the base line

Step two of paper chromatography

Add a drop of ink containing different substances to the line

Step three of paper chromatography

Fill a beaker with the solvent (water or ethanol)

Step four of paper chromatography

Place the paper in the solvent just below the line

Step 4.5 of paper chromatography

You can put a lid on the beaker to stop the solvent evaporating

Step 5 of paper chromatography

Wait for the solvent to rise up the paper and display the different inks (insoluble inks won’t rise)

Step six of paper chromatography

When the solvent reaches the top of the paper, take it out and wait for it to dry

Mobile phase

The substance the molecules can move in- the solvent

Stationary phase

A substance the molecules can’t move in- the paper

More soluble inks…

Move faster

Rf value:

Distance travelled by spot/distance traveled by solvent

Screening

Removing anything large

Sedimentation

Heaviest bits of mixture sink to the bottom, lighter bits float

Sewage filtration

Small particles are filtered through sand and gravel

Chlorination

Chlorine is added to the water to kill microorganisms

potable water

water safe to drink

what does potable water often include

other dissolved substances, making it impure

criteria for potable water- substances

levels of dissolved substances needs to be low

criteria for potable water- pH

needs a pH between 6.5 and 8.5 to not be too acidic/alkaline

criteria for potable water- microorganisms

there can’t be any microorganisms in it

surface water

bodies of water exposed at the surface

advantages of surface water

easy to access, replaced constantly by rain

disadvantages of surface water

can dry up easily on hot and sunny days

aquifers

underground permeable rocks that trap water

step one of making water potable- wire

filter it through a wire mesh to filter out any big things

step two of making water potable- sand

filter it through sand and gravel to remove small solids

step three of making water potable- sterilize

sterilize it to kill harmful microorganisms

how can you sterilize water

bubble chlorine gas through it or expose it to ozone/uv light