The author replies to Tóth.

Clearly, it is not a multiple-stoichiometry equation, since five nonequivalent atomic conservation relations are available to assign the six stoichiometric coefficients, so that it can be readily balanced by the algebraic method (1). The same is no more true when employing the (traditional) oxidation-number method, because ethanol gives origin to two different oxidation products (each containing carbon with a different oxidation number) such that the ratio of their amounts (numbers of moles) cannot be established a priori. Minor difficulties arise from the facts that the (only) reduction product (formally) takes origin from two different species, one of which is also the source of the oxidation products; furthermore, in this equation, hydrogen plays a dual function (2), partly behaving as a redox, and partly as a non-redox, element.

Therefore, Tóth's equation represents a third case where, while the traditional oxidation-number method fails, our approach, which splits the equation into two simpler ones, each involving the participation of the same "extraneous" species as co-reactant and co-product, succeeds; the other two cases are the double disproportionations (3) and the rather uncommon equations of the kind elsewhere (4) discussed by us, for which we would propose the name of dis-co-proportionations.

Finally, we would observe that Tóth's equation could have been balanced also by employing the recently published (5) more general version of the oxidation-number method which makes use of oxidation-number concepts in an algebraic-method framework.

Literature Cited

1. Porter, S. K. J. Chem. Educ. 1985, 62, 507-508.

2. Kolb, D. J. Chem. Educ. 1978, 55, 326-331.

3. Cardinali, M.E.; Giomini, C.; Marrosu, G. J. Chem. Educ. 1995, 72, 716.

4. Giomini, C.; Marrosu, G.; Cardinali, M. E. Educ. Chem. 1994, 31, 67.

5. Cardinali, M. E.; Giomini, C.; Marrosu, G. Educ. Chem. 1996, 33, 51-52.