Lesson 8 What is a mixture?
Learning objectives. Pupils should
6/8a be able to define a mixture
6/8b be able to draw particle pictures to represent elements compounds and
mixtures
6/8c be able to identify suitable methods for separation of mixtures
PowerPoint U6.8P1 is available to support the lesson.
Possible Activities
Activity 1 [objectives 8a and b]
Ask the class working in small groups to give their definition of the word pure. As a
stimulus ask what supermarkets mean by 'pure orange juice' or 'pure mineral water'.
The discussion should draw out the scientific meaning of pure - a single substance
and compare with the everyday use.
Pure orange juice is only orange juice but contains more than one substance - water,
sugar, vitamin C, citric acid etc.
Go on to establish particle pictures of pure and impure substances.
U6.8W1 is a card sort activity that you can use to promote discussions.
Reference in KS3 revision book p74.
Activity 2 [objective 8c - review of work in Unit 5 Solutions etc]
This activity is a circus in which pupils identify the most suitable method for the
separation of a mixture.
Each station has a prompt card and the mixture. Pupils should record the method and
property of the materials that allows separation. A mixture of different coloured
marbles could be used to introduce the activity. It is more important that pupils do
some examples well than all not so well.
Reference in KS3 revision book p76/77 Eg.
Mixture
coloured marbles
Separation method
by hand
Important property
colour
Before starting the circus draw up a list of techniques on the board to act as a prompt.
Techniques - chromatography, distillation, evaporation, filtering, magnetism.
There are also diagrams of distillation and chromatography on pages 46 and 47 of
spectrum chemistry.
The mixtures:
felt pen ink
chalk in water
salt water (obtain the water)
copper sulphate solution (obtain copper sulfate crystals)
iron filings and sulfur powder
Plenary
PowerPoint U6.8P1 has a quiz at the end. The quiz recaps compounds, formulae and
separation techniques.
Possible homework
Draw labelled scientific diagrams of the apparatus they would use to carry out the
separations
Or complete worksheet U6.8W1 methods of separation.
Resources: Lesson 8
Activity
1
2
Resources
U6.8W1 Card sort. Technicians-Folder
Room L50B)
Circus cards Technicians -Folder Room
L50b
Tray L56 including
Felt pens x 3
Chalk powder in water x 3 labelled
beakers
Salt water x 3 labelled beakers
Copper sulfate soln x 3 labelled beakers
Iron filings and sulfur powder mix x 3
Homework
Spectrum chemistry
U6.8W2 methods of separation