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Go to module 8 worksheets (click on red cross)
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Use the first sheet to see how the formulae is found. Use the second worksheet to reinforce, then try the examples 1-12.

Link to Homework

D. Properties of ionic compounds

Ionic compounds are able to conduct electricity when molten (melted) or in aqueous solution.

Why? The ions are free to move so can carry the electric charge around a circuit

Ionic compounds also tend to have high melting and boiling points due to the strong electrostatic forces of attraction that hold the ions together.

E. Making Electricity from chemicals

A simple electric cell (battery) can be made by immersing 2 different metals in an electrolyte ( an aqueous solution of an ionic compound) and connecting them with a conducting wire. A current flows through the wire.

In the above experiment we would get a reading on the voltmeter which shows that chemical energy has been converted into electrical energy.

Explanation:

The zinc rod dissolves by giving up electrons and going into solution as zinc ions

The electrons move through the circuit via the voltmeter to the copper rod.

Here the electrons are taken by aqueous copper ions to form copper metal which is seen forming on the surface of the copper rod.

Cu2+(aq) – 2 electrons

Cu(s)

The electrons that flow from the zinc rod to the copper rod make the electric current.

Link to experiment on electricity from chemicals

F. Extension: Electrolysis

Electrolysis is the breakdown of a substance by electricity. You will have seen evidence of this in the experiment where aqueous solutions of ionic compounds conduct electricity.

Electrolytes are compounds which do not conduct electricity when solids, but do when molten or in aqueous solution. Examples: Ionic compounds. The ions are free to move and hence carry electric charge.

As you can see above there is a flow of electrons from the negative to the positive.
The ions carry the electric charge through the solution to complete the circuit.

Link to homework on electrolysis

• Introduction
• Information : Atoms
• Information : Ions
• Practical Work
• Homework Activities
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