Mixtures, compounds and properties
Answers are for parents and teachers.
1
List four mixtures and two pure substances that you find in the kitchen.
Answers differ: mixtures such as orange juice, milk, tea and air; pure substances such as sugar and aluminium foil.
2
Plan how to separate a mixture of salt, sand and iron nails. Write the steps in order.
Use a magnet to take out the nails. Add water and stir. Filter to take out the sand. Let the water evaporate in a saucer on a sunny windowsill to get the salt.
3
A molecule has 2 hydrogen atoms and 1 oxygen atom. Write its formula and say if it is an element or a compound.
H₂O; a compound, because it has two kinds of atoms.
4
Egyptian blue has the formula CaCuSi₄O₁₀. How many atoms does one unit hold in all?
1 + 1 + 4 + 10 = 16 atoms.
5
Give one physical property and one chemical property of iron.
Physical: it is shiny and attracted by a magnet. Chemical: it rusts in damp air.