Mixtures and Separating Mixtures

Mixtures Many of the ordinary things around us are mixtures of a number of different substances. A mixture is made of two or more different substances mingled with each other but not chemically combined.

sea water: a mixture of salts and water Sea water is a mixture of water, salt, and a number of other substances. Crude oil is one of the most valuable mixtures ever discovered! sea water: a mixture of salts and water

More examples of mixtures: Cola, Petrol..

When substances are separated from mixtures they are said to be purified The method of separation depends on the type of mixture.

Filtration is a method of separating an insoluble solid from a liquid

Each particle in the water is 3mm in diameter FILTRATION - Choose the sieve!! Each hole is 2.5 mm wide Each hole is 10 mm wide Each particle in the water is 3mm in diameter Have a kitchen sieve and water/peas or flour/peas mixture to demonstrate sieving. Read the sizes of the sieve holes and diameter of the particles in the water of the beaker. Ask the pupils to choose the correct sieve.

FILTRATION Filter funnel with 2.5 mm sieve Well done the sieve size is smaller than the particles so only the water gets through! Conical Flask Click on the red label to start the animation. Start

FILTRATION Filter funnel with 10 mm sieve Nope! the sieve size is larger than the particles so both the water and particles get through! Conical Flask Click on the red label to start the animation. Start

Set up your apparatus like this:

Separating Mixtures Filtration Everyday examples of filtration: A coffee filter is a piece of paper that separates the coffee solution from the coffee grounds. An extractor fan above a hob oven removes fumes and smells from the cooking area.

Check your learning.. What is a mixture? Why is the sieve size important for filtration? What does insoluble mean? Give two examples of mixtures that can be separated by filtration. What is the filtrate? What is the residue?

Mixtures and Separating Mixtures Ms. O’ Grady 1st year Science Separation Techniques -Evaporation

Separation Techniques -Evaporation Sometimes mixtures can be separated by using evaporation… Evaporation is used to separate a soluble solid from a liquid. Ms. O’ Grady 1st year Science Separation Techniques -Evaporation

Separation Techniques -Evaporation Time 100oC Particles in water 70oC Water heats up Water begins to evaporate 20oC Water continues evaporating All water evaporated – particles remain Run through apparatus above. Mention that thermometer shows water temperature. Start Ms. O’ Grady 1st year Science Separation Techniques -Evaporation

Separation Techniques -Evaporation Ms. O’ Grady 1st year Science Separation Techniques -Evaporation

Set up your apparatus like this: Ms. O’ Grady 1st year Science Separation Techniques -Evaporation

Separation Techniques -Evaporation Evaporation is used to separate sodium chloride from a mixture of sodium chloride in water. When the mixture of sodium chloride and water is heated the water particles turn from a liquid to a gas and then escape from the beaker The sodium chloride is left behind in the evaporating dish Ms. O’ Grady 1st year Science Separation Techniques -Evaporation

This can come in very useful! In desalination plants fresh water can be made from salty sea water by using evaporation! A desalination plant in Australia Ms. O’ Grady 1st year Science Separation Techniques -Evaporation

Check your learning.. What is a mixture? What does soluble mean? How does evaporation work? What is the disadvantage of separating a mixture by evaporation?

Mixtures and Separating Mixtures Ms.O’ Grady 1st year Science Separating techniques - Chromatography

Separating techniques Chromatography Chromatography is a way to separate mixtures like a mixture of dyes in ink. Ms.O’ Grady 1st year Science Separating techniques - Chromatography

Separating techniques What happens to the ink?? Ms.O’ Grady 1st year Science Separating techniques - Chromatography

Separating techniques CHROMATOGRAPHY Take a piece of filter paper Add the coloured ink in small blobs Here Here Here Mention that numbers on blobs are it’s ‘weight’. Brown is a mixture of red and blue so has a ‘weight’ of 3, with red a ‘weight’ of 1 and blue a ‘weight’ of 2. 1 2 3 Draw a Pencil Line Ms.O’ Grady 1st year Science Separating techniques - Chromatography

Now leave for about 15 minutes CHROMATOGRAPHY Beaker with a little water Water moves up the paper and so do the inks Now leave for about 15 minutes 2 2 2 2 1 2 1 1 2 3 Mention calculation of Rf values. 1 2 3 Start Ms.O’ Grady 1st year Science Separating techniques - Chromatography

Which person do you think did the graffiti on the wall? Ink from graffiti Ink from suspect A Ink from Suspect B Ink from suspect C Ms.O’ Grady 1st year Science Separating techniques - Chromatography

Learning check.. Give an example of a type of mixture separated by Chromatography? How does chromatography work? What would happen if a mixture was made up of just one colour?

Mixtures and Separating Mixtures

Distillation is used to separate a mixture of a liquid and a soluble solid when the liquid is needed Can you explain what is happening in this experiment?

DISTILLATION Cold water out! Cold water in! Start 100oC 70oC 20oC Run through apparatus above. Mention that thermometer shows water temperature. Describe apparatus and describe process as it occurs. Start

Distillation is used to separate a mixture of liquids when the liquids have different boiling points! What happens to the alcohol when it reaches 78 OC? What happens to the water when it reaches 78 OC?