Using the filtration method
The filtration method is good for separating an insoluble solid from a liquid. (An insoluble substance does not dissolve in water.)
You are going to separate a mixture of water and sand using this method.
The liquid passes through the filter, but the solid particles cannot go through.
Materials
– water – a beaker
– a funnel – some filter paper – a container for the mixture of water and sand
1
. Put the funnel into the beaker. Place the filterpaper in the funnel.
2
. Pour the mixture into the filter paper.3
. Remove the sand that has stayed behind in the filter paper.Using the decanting method
The decanting method is useful for separating a heterogeneous mixture of two liquids that have a different density.
You are going to separate a mixture of water and oil using this method.
Materials
– water – oil – spoon
– a container for the mixture of water and oil
1
. Leave the mixture to rest until the particles of the liquid with the least density (oil) settle on top of the particles with the highest density (water).2
. Use a spoon to separate the liquid that is at thetop of the beaker.
Activities
10. Does sand dissolve in water?
Is a mixture of sand and water homogeneous or heterogeneous?
11. Copy and complete the text.
Sand dissolve in water. When you mix sand and water you get a mixture. Sugar in water to form a solution. A solution is a mixture.
6.
What are synthetic materials?
Synthetic materials do not exist in nature. They are obtained fromnatural substances which are transformed by chemical processes. Synthetic materials are used to manufacture many products in modern, industrialised societies because of their special properties. Some of the most popular synthetic materials are:
Plastic. Most plastics are made from petroleum. There are many
different kinds, used to make a multitude of things.
Glass is made from silica.
Fibreglass is made from extremely fine fibres of glass, woven
together.
Fibre optic is a fibre made of glass or plastic. It is a long, fine tube
which light travels along.
Carbon fibre is made up of mainly carbon atoms. It is an extremely
thin fibre. Each fibre is incredibly strong. The fibres are woven together to create a very resistant material.
Activities
12. What materials would you use to make the following products? a. a boat b. a modern office building c. parts of an aeroplane d. a strong container to hold water e. a cable for telephones Say why in each case. 13. What properties of
carbon fibre make it ideal for making a bicycle?
Material Plastic Glass Fibreglass Fibre optics Carbon fibre
Properties – impermeable
– light, flexible – resistant – does not rust
– fragile, but hard – does not rust – lets light through
– flexible and strong – does not rust
– excellent
conductor of light – does not rust
– light – resistant – elastic – does not rust
Used for multiple uses multiple uses boats, car bodies cables for
telephones, computers
cars, bikes, tennis rackets, aeroplanes
Some properties of synthetic materials
Fibre optics can conduct vast quantities of light or information at very high speed Equipment for water sports is often
made of fibre glass Carbon fibre is strong but elastic.
It has many uses in aviation
Every year, modern societies generate more and more rubbish. Urban solid waste is unwanted solid and semi-solid materials from homes, commerce and industry.
This waste can be harmful to the environment. Some of it is toxic. It needs to be treated or recycled.
What can you do to help?
You can reduce solid waste in the home, and recycle some of it. Recycled materials can be transformed into new raw materials.
7.
Why is recycling important?
plastics 7 %
metals 8 % other 10 %
glass 10 % organic matter 30 % paper 25 % textiles 10 %
Solid waste: example
DO
Reuse materials: plastic bags, writing paper. Recycle paper, glass, tins and plastic. Take old medicines, paints and batteries to collection dumps. Use rechargable batteries. DON’T
Buy things with a lot of unnecessary packaging. Dump rubbish on the beach or in the countryside.
What happens to recycled waste?
domestic consumption processing and manufacturing waste collection transport recycling process incineration raw materials glass paper metal plastic compost rubbish dump toxic waste waste collection
Activities
14. Copy and complete the table about waste in your home.
15. Make a Do / Don’t poster about how to help reduce solid urban waste.
16. Investigate how urban solid waste is removed in your own area.
Organic Toxic Recyclable
vegetables leaves medicines paints bottles newspapers 877306 _ 0140-0149.qxd 18/2/08 09:13 Página 147
Activities
17. Read and classify: solid, liquid or gas. a. oxygen d. hydrogen g. salt
b. water e. oil h. iron
c. granite f. steam
18. Identify: element, compound, mixture.
19. Copy and complete the table with the properties of the three different states.
20. Give reasons for your classification in activity 17. 1. It flows easily.
2. It is easy to compress. 3. It cannot be compressed. 4. It has no fixed shape. 5. It has a fixed shape.
6. It has a fixed volume and shape. 7. It takes the shape of its container. 8. It can spread out into a space.
Example: a-4. Oxygen is a gas: it has no fixed shape. 21. Classify the changes: physical or chemical.
Give a reason.
a. Paper is burned and changes into ashes. b. A rusty piece of metal.
c. Clothes drying in the Sun. d. Lava cools down and solidifies. e. Water is broken down into hydrogen
and oxygen.
22. Could you make a solution of the following substances? Say why or why not in each case. -cornflakes and milk -water and oil
-butter and salt -water and ink
23. Can mixtures be compounds? Why or why not? Hint: A chemical compound consists of two or more elements joined up.
24. Copy and complete the following phrases. a. The change from solid to liquid is called… b. The change from gas to liquid is called… c. The change from liquid to gas is called… d. The change from liquid to solid is called… 25. Indicate the solvent, the solute and the solution in
this drawing.
26. All substances can be found in any one of the three states of matter, if the conditions are right.
a. Is it is possible to find iron in a liquid state on Earth? b. Is it possible to find water in a gaseous state? 27. Draw how you think particles of air are organised
inside a container. Represent the air particles with dots. Then, draw the particles again after half the air has been removed.
28. Cartons are made with several layers of cardboard and polyethylene. The polyethylene is in contact with the liquid. It is a light plastic that does not let in air, humidity or bacteria. Cardboard makes the container harder.
a. Why is polyethylene a good material to store food? b. What would happen if the container were made
only of cardboard?
29. If you wash up a glass and leave it to dry, what has happened to the water on the glass? Would it dry faster in a cold room or a warm one? Why? What is the name of this process?
Shape Volume Flows / does
not flow Solids Liquids Gases A B C C It’s a chemical
physical change because the substance
is the same. changes.
A
B
Physical states
Matter can exist in three different physical states: • Solid: Fixed shape and volume. High density. • Liquid: No fixed shape. Fixed volume. It can flow.
Quite high density.
• Gas: No fixed shape. No fixed volume. It can flow and be compressed. Low density.
A substance can change from one state into another.
Particle theory
• Matter is made up of tiny particles, surrounded by empty spaces.
• The particles within matter are in constant motion. • There are forces which attract the particles. Particle theory describes changes from one state into another.
EVERYTHING IS MATTER
What should you know?
Mixtures
Matter can be classified by its appearance as:
• Heterogeneous: the appearance is not uniform. The components can be distinguished.
• Homogeneous: appearance is uniform. The components cannot be distinguished. Most common substances are mixtures.
Solutions are homogeneous mixtures of two or more substances, made up of:
• a solvent: the most abundant component. • a solute: the least abundant part of a solution.
Solid Liquid Gas fusion solidification sublimation regressive sublimation vaporisation condensation F F G F G G Pure substances
There are two types:
• Chemical compounds: Can be broken down chemically into simpler substances. • Elements: Cannot be broken down into simpler substances
INVESTIGATE:Research other methods for separating mixtures. Display the results in a poster.
Use diagrams and explanations.
WEB TASK:What is the fourth state of matter? Investigate.