Making Electricity

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Slide 9

Magnesium is higher in the electrochemical series than copper.

Magnesium gives electrons to the copper ions.

The copper ions gaining these electrons form copper atoms (brown solid).

The magnesium atoms lose electrons to form colourless ions which dissolve in the solution.

Slide 10

The solution was blue due to the copper(II) ions.

As the copper ions are being changed to copper atoms, the blue colour fades.

The copper ions have been displaced from the solution as copper atoms.

A displacement reaction will occur when a metal is placed in a solution of metal ions, if the metal is higher in the electrochemical series than the metal ions.

Slide 11

Ion-electron equations can be used to show the reaction (use page 7 of data booklet).

Start with

Mg atoms

End with

Cu atoms

Mg atoms lose electrons to form Mg ions

Electrons given to Cu ions

Cu ions gain electrons to form Cu atoms

Slide 12

The ion-electron equations can be re-written to show each step in the reaction:

Slide 13

Electricity can be produced by connecting two different metals in solutions of their metal ions.

to the lower metal.

Electrons flow in the wires

from the metal high in the electrochemical series

Ion bridge/salt bridge

Slide 14

The purpose of the “ion bridge” (“salt bridge”) is to complete the circuit.

through the ion bridge/salt bridge.

Ions flow through solutions and

Ion bridge/salt bridge

The movement of ions through the ion bridge completes the circuit.

Slide 15

Cells/batteries compared to mains electricity.

Ease of transport:

cells/batteries are highly portable / mains electricity is not!

Safety:

cell/battery voltages/currents are safer than those of mains electricity.

Costs:

cells/batteries are much more expensive.

Uses of finite resources:

making cells/batteries uses up more finite resources than producing mains electricity.

Slide 16

Reactions of metals with dilute acids can establish the position of hydrogen in an electrochemical series, e.g. Magnesium and hydrochloric acid

Start with

Mg atoms

End with

H molecules

Mg atoms lose electrons to form Mg ions