Note:
IGCSE Chemistry Notes on Electricity and Chemistry
5.1 Electricity and chemistry
Core
- Define electrolysis as the breakdown of an ionic
compound, molten or in aqueous solution, by the
passage of electricity
- Describe the electrode products and the
observations made during the electrolysis of:
– molten lead(II) bromide
– concentrated hydrochloric acid
– concentrated aqueous sodium chloride
– dilute sulfuric acid
between inert electrodes (platinum or carbon)
- State the general principle that metals or
hydrogen are formed at the negative electrode
(cathode), and that non-metals (other than
hydrogen) are formed at the positive electrode
(anode)
• Predict the products of the electrolysis of a
specified binary compound in the molten state
- Describe the electroplating of metals
- Outline the uses of electroplating
Supplement
- Relate the products of electrolysis to the
electrolyte and electrodes used, exemplified
by the specific examples in the Core together
with aqueous copper(II) sulfate using carbon
electrodes and using copper electrodes (as used
in the refining of copper) '
- Describe electrolysis in terms of the ions present
and reactions at the electrodes in the examples
given
- Predict the products of electrolysis of a specified
halide in dilute or concentrated aqueous solution
- Construct ionic half-equations for reactions at
the cathode
Core
- Describe the reasons for the use of copper and
(steel-cored) aluminium in cables, and why
plastics and ceramics are used as insulators
Supplement
- Describe the transfer of charge during electrolysis
to include:
– the movement of electrons in the metallic
conductor
– the removal or addition of electrons from the
external circuit at the electrodes
– the movement of ions in the electrolyte
- Describe the production of electrical energy from
simple cells, i.e. two electrodes in an electrolyte.
(This should be linked with the reactivity series in
section 10.2 and redox in section 7.4.)
- Describe, in outline, the manufacture of:
– aluminium from pure aluminium oxide in
molten cryolite (refer to section 10.3)
– chlorine, hydrogen and sodium hydroxide
from concentrated aqueous sodium chloride
(Starting materials and essential conditions
should be given but not technical details or
diagrams.)