Rusting and Acetic Acid

Name: Kristel
Status: student
Grade: 6-8


Question: Which occurs first in the rusting of iron by acetic acid
solution: the rusting or the hydrogen bubbles?
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Kristel,
 
Since the formation of rust is essentially an oxidation-reduction 
reaction in which the iron (Fe with an oxidation state of zero) is 
oxidized to Fe(2+) or Fe(3+) and the hydrogen ion, H(+) is reduced 
to H2(g) with an oxidation state of zero, then it can be said that 
the oxidation and reduction occurs simultaneously since in this type 
of reaction, no oxidation can occur without the corresponding reduction.
 
Greg (Roberto Gregorius)
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Since they are both products of the same reaction, they appear 
simultaneously. Depending upon your set up you may observe one or the 
other first, but they are produced simultaneously.

Vince Calder
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They are actually separate reactions.  The iron can rust without 
liberating hydrogen. 

The hydrogen-liberating reaction is reduction of hydrogen:

  2 Fe(s) + 6 HOAc --> 2 Fe(OAc)3 + 3 H2

The rusting of iron is air-oxidation:

  2 Fe + 3 O2 --> Fe2O3

Richard Barrans
Department of Physics and Astronomy
University of Wyoming
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