B17 Corrosion of Aluminum
Description
Aluminum is protected from oxidation by a coating of aluminum oxide which is impervious to many chemicals. Strips of aluminum are amalgamated with mercury which prevents the formation of this impervious layer. Amalgamated aluminum oxidizes in air, plates copper out of a copper(II) solution, and dissolves in water with the evolution of hydrogen. Standard reduction potentials predict that these reaction will be spontaneous. Aluminum with the normal oxide coating is shown for comparison.
Equation
4 Al + 3 O2 --> 2 Al2O3
2 Al + 3 Cu2+ --> 3 Cu + 2 Al3+
2 Al + 6 H+ --> 2 Al3+ + 3 H2
Reference
H. N. Alyea and F. B. Dutton, Eds.,"Tested Demonstrations in Chemistry", 6th ed., Journal of Chemical Education, Easton, Pennsylvania (1965) p.131.
J. L. Roberts,Jr. and J. B. Ifft,"Frantz/Malm's Chemical Principles int the Laboratory", W. H. Freeman and Company, San Francisco, California, (1977), p 398.