1. Mixtures and Separating Mixtures

2. 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.

3. 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

4. More examples of mixtures: Cola, Petrol..

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

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

7. 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.

8. 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

9. 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

11. Set up your apparatus like this:

12. 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.

13. 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?

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

15. 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

16. 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

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

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

19. 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

20. 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

21. 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?

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

23. 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

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

25. 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

26. 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 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

27. 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

28. 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?

29. Mixtures and Separating Mixtures

30. 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?

31. 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

32. 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?