8.1) The diagrams in the boxes show different arrangements of particles.

Give the letter of the diagram which represents:
a: molecules of a compound
b: molecules of an element
c: atoms of a mixture
d: atoms of an element

8.2) Copy and complete these sentences using words from the list. You may use each word once, more than once or not at all.
dissolve mixture solvent
dissolves saturated temperature
evaporates solid volume
filtrate solute
insoluble solution
Two or more substances mixed together are called a ..........a......... A solute is a solid that ........b.......... in a liquid. The liquid that it dissolves into is called a .........c.......... Together they make a .........d.......... A solid that does not dissolve in a liquid is called ..........e.......... .
If a solution is left for a few days the water ........f......... and a .......g........ is left in the container.
If a solid is added to a liquid until no more of the solid will dissolve a .........h............ solution is formed.
The solubility of a solid measures how much of the solid will ........i......... .
When you measure the solubility of a solute you must use the same ......j....... and type of the solvent at a given .......k..........

8.3) The table below gives the colours and solubility in water of four compounds.

The compounds were added to separate beakers of water. There was enough water to completely dissolve the soluble compounds. The contents of each beaker were filtered.
a: One of the compounds left a white solid in the filter paper.
What is the name of this compound?
b: What would be the colour of the filtrate from this beaker?
c: Describe how you would obtain pure crystals of iron sulfate from a mixture of copper carbonate and iron sulfate.

8.4) Ibrahim and Emmanuel have been investigating the amount of copper sulfate that can be dissolved in water at different temperatures. They added copper sulfate until no more would dissolve and they carefully measured the mass of the copper sulfate they added. Here are their results.

a: What is the range of temperatures that the boys used?
b: What interval did they use for the temperatures?
c: Name a variable the boys should have kept the same.
d: Which is the independent variable?
e: Plot a graph of their results.
f: What conclusion can the boys make from their results?