Measurement
Techniques - Purity
Mr. Kaburu’s resources
Lesson Objectives
To define purity,
mixture, solute,
solvent, solution
Discuss filtration
& decanting
Task 1: Sea water
question
• What is the difference between sea
being
andwater?
nothing
waterthat
and river
(1 mark)
• Sea water
elsehas a lot of salt (Sodium
Chloride, NaCl)
• Are the two types of water pure?
Explain (2 marks)
• No
• Pure water does not contain any
solutes
Methods of Separation
• Separating – To divide and move away from another
• Question: How can we separate sand and salt? (Words:
Dissolve, Filter, Boil) (3 marks)
• Dissolve the mixture in water – only salt and soil will dissolve
• Filter to remove the residue
• Boil the filtrate until all the water has evaporated to leave
the salt
• Separating sand
and salt.
Filtration
Task 2: The oil question
• While cooking, Jill’s oil poured into a pot
containing water. She wanted to use the water
to boil cook rice.
• Suggest a way of separating the oil from the
water. State the Physical property that your
method relies upon (Uses)
Model Solution
• Water has a higher density than oil
• Oil will float on water
• The oil is decanted into another container
Recap
Method
Property it uses
• Filtration
• Size of molecules
• Decanting
• Density
• Boiling
• Boiling point
Task 3
•Answer the
questions
provided