Mixtures and Mixtures and SeparationSeparation

Topic: Separation Techniques in ChemistryTopic: Separation Techniques in ChemistrySection A-Principles of Chemistry (CSEC)Section A-Principles of Chemistry (CSEC)Teacher/Tutor: Miss BartleyTeacher/Tutor: Miss Bartley

Properties of MatterProperties of Matter Physical properties:Physical properties: characteristics of a material which characteristics of a material which

may be determined without altering the composition of may be determined without altering the composition of the material; bp (boiling point), mp, color, density etc., the material; bp (boiling point), mp, color, density etc., no change in the chemical identity occurs.no change in the chemical identity occurs.

Chemical properties:Chemical properties: characteristics of a material characteristics of a material which involves altering the composition of the material. which involves altering the composition of the material. A rearrangement of the atoms. A rearrangement of the atoms.

Phase:Phase: a sample of matter that is uniform throughout, a sample of matter that is uniform throughout, both in its chemical composition and its physical state.both in its chemical composition and its physical state.

Chemical Bonds:Chemical Bonds: the attractive forces, “ the glue”, the attractive forces, “ the glue”, strong enough to maintain a group of atoms together strong enough to maintain a group of atoms together for an indefinite amount of time.for an indefinite amount of time.

How is matter broken How is matter broken down..down..

T H E MO LEC U LAR T H EO R Y O F MAT T ER

COM POUNDS ELEM ENTS

PURESUBST ANCE

HOM OGENEOUSM IXTURE(S o lu tion )

HETEROGENEOUSM IXTURE

M ATT ERSeparated by physical methods

Separated by physical methods

Separated by chemical methods

Separated by physical methods

DefinitionsDefinitions Matter :Matter : occupies space. Has weight and mass. occupies space. Has weight and mass. EnergyEnergy : the ability to do work : the ability to do work

Materials:Materials: a particular type of matter, generic term. a particular type of matter, generic term.

Mixture:Mixture: has variable composition, can be separated has variable composition, can be separated by physical methods.by physical methods.

Heterogeneous mixtureHeterogeneous mixture: has properties which vary : has properties which vary from region to region, can be separated into a from region to region, can be separated into a homogeneous mixture or a substance.homogeneous mixture or a substance.

Homogeneous mixtureHomogeneous mixture: uniform properties : uniform properties throughout, also called a solution. Can be separated throughout, also called a solution. Can be separated into substances.into substances.

DefinitionsDefinitions (Pure) substance: a material which cannot be

separated by physical methods into 2 or more materials which have different characteristics.

Compounds: a material containing two or more elements or molecules.

Molecules: A group of 2 or more atoms held together by strong forces called "bonds".

Atoms: the smallest particle of matter which has distinctive chemical characteristics, composed of a nucleus surrounded by electrons.

Elements: a specific substance which cannot be decomposed into simpler substances by chemical means. An atom with a specific number of protons, neutrons, and electrons.

Breaking it down to pieces…

Separating Mixtures

Separating MixturesSeparating Mixtures

Mixing sulphur and iron...Mixing sulphur and iron...

...how could you separate this mixture?

Separating MixturesSeparating Mixtures

Do notDo not put magnetic directly put magnetic directly on ironon iron

Hold the magnet Hold the magnet belowbelow the Petri the Petri dishdish

Magnet

Petri dish

Sulphur + Iron mixture

Separating MixturesSeparating MixturesYou’re You’re strandedstranded on a desert island surrounded by on a desert island surrounded by

sea water, sadly your sea water, sadly your science teacher is lostscience teacher is lost at sea but at sea but luckily all your luckily all your science equipment has washed upscience equipment has washed up... ...

...how could you separate a mixture of sand, salt ...how could you separate a mixture of sand, salt and water to get drinking water?and water to get drinking water?

GoalGoal: to extract clean : to extract clean fresh waterfresh water

Come up with a plan, you will need:Come up with a plan, you will need:- A list of equipmentA list of equipment- A series of stepsA series of steps

You should be able to explain your You should be able to explain your reasoning for each step, use your reasoning for each step, use your science knowledge!science knowledge!

You have 10 minutesYou have 10 minutes

Separating MixturesSeparating Mixtures

Used for separatingUsed for separating suspensionssuspensions. Eg . Eg chalk in water, soil in chalk in water, soil in water, sand in water.water, sand in water.

Filtration at home…Filtration at home…

Separating Mixtures: Separating Mixtures: EvaporationEvaporation

Use for making mixtures more concentrated by Use for making mixtures more concentrated by driving off solvent molecules.driving off solvent molecules.

Mixture (salt and water)

Bunsen burner

Evaporation in use..Evaporation in use..

Separating Mixtures: Separating Mixtures: Simple DistillationSimple Distillation

Used for separatingUsed for separating solutions. solutions. Eg salt Eg salt water, solutions of water, solutions of liquids that have liquids that have different boiling different boiling points like alcohol in points like alcohol in water etc water etc

What is happening

here?

Separating Mixtures - Separating Mixtures - LiquidsLiquids

How could we separate a mixture of How could we separate a mixture of waterwater and and alcoholalcohol??

Alcohol boils at 78CWater boils at ? C

If you heated a mixture of water and alcohol which would boil first?

Fractional DistillationFractional Distillation Used for separating mixtures Used for separating mixtures

of of liquidsliquids in fractions due to in fractions due to their boiling points.their boiling points.

The liquids boil at different The liquids boil at different levels of the distillating levels of the distillating column. The ones with lower column. The ones with lower boiling point will boil first and boiling point will boil first and are collected in the top are collected in the top section while the higher section while the higher boiling point liquids will collect boiling point liquids will collect at lower level in the column.at lower level in the column.

Eg. Fractional distillation of Eg. Fractional distillation of crude oil gives us different crude oil gives us different liquids such as cooking gas, liquids such as cooking gas, petrol, kerosene, chemicals petrol, kerosene, chemicals for making plastics etc for making plastics etc

ChromatographyChromatography

Used for separating Used for separating coloured mixtures coloured mixtures based on their based on their attraction to a attraction to a stationary phase and stationary phase and a mobile phase. a mobile phase.

Eg. Separating dyes, Eg. Separating dyes, pigments, inks, food pigments, inks, food colouringscolourings

Paper ChromatographyPaper Chromatography

Retention factor = distance travelled by spot / distance travelled Retention factor = distance travelled by spot / distance travelled by solventby solvent

Chromatography at Chromatography at home…home…

Making copper sulphate Making copper sulphate crystals from a solution..crystals from a solution..

Crystallization at home…Crystallization at home…

Make a saturated solution of table salt.Make a saturated solution of table salt. Boil the solution so that some of the water Boil the solution so that some of the water

molecules evaporate.molecules evaporate. Cool the mixture on ice and you will see Cool the mixture on ice and you will see

salt crystal forming out of the solution!salt crystal forming out of the solution!

Solvent ExtractionSolvent Extraction

This is the process of dissolving one of the This is the process of dissolving one of the components of a mixture in a particular liquid (eg components of a mixture in a particular liquid (eg water) while the other components will not dissolve. In water) while the other components will not dissolve. In this way, we can separate the water solution from the this way, we can separate the water solution from the other undissolved components.other undissolved components.

Eg. A mixture of iron fillings and sulphur is separated Eg. A mixture of iron fillings and sulphur is separated

by using carbon disulphide as solvent. Carbon by using carbon disulphide as solvent. Carbon disulphide will dissolve only the sulphur and NOT the disulphide will dissolve only the sulphur and NOT the iron fillings so we can then proceed to separate the iron iron fillings so we can then proceed to separate the iron fillings from the mixture.fillings from the mixture.

Solvent extraction in the Solvent extraction in the lablab

Separation Techniques in Separation Techniques in industry…industry…

YoutubeVideo - Manufacture of YoutubeVideo - Manufacture of sucrose from sugar cane.sucrose from sugar cane.

YoutubeVideo - Purification of YoutubeVideo - Purification of water by reverse osmosis.water by reverse osmosis.

ReferencesReferences

www.slideshare.netwww.slideshare.net www.youtube.comwww.youtube.com Chung-Harris, T. Taylor, M. (2009). 2Chung-Harris, T. Taylor, M. (2009). 2ndnd

Ed. Chemistry for CSEC.Ed. Chemistry for CSEC.