15. Electrochemistry

Electroplating

In electroplating, a 'cheap' metal is coated with a layer of a more expensive metal.

Electrolysis

Electrolysis can also be used to split ionic compounds. This can be a very useful of separating expensive and reactive metals such as Mg and Al from their compounds.

BUT the reactivity of the species produced can affect what products are actually made.

E.g. Watch the demonstration of the electrolysis of a sodium chloride solution.

What do you predict will be made at each electrode?

What would be the half equation for these reactions?

What is actually made at each electrode?

Why?

Answer the questions on the electrolysis of solutions sheet.

The 'cheap' metal is used as the cathode in an electrolytic cell and the more expensive metal is the solution that it is placed in. The anode just has to be able to conduct electricity.

Activity: If I wanted to coat a cheap piece of copper metal in silver to make a piece of jewellery what would my equipment set-up look like?

Sketch a diagram to show what goes where:

Equipment:

• • Silver nitrate solution

  • Battery (9V)

  • Bulb

  • Wires

  • Copper electrode

  • graphite electrode

Key words:

• • cathode

  • anode