How do you solve and represent #"disproportionation reactions"#? Is there an easy way to do this?

1 Answer
Aug 16, 2017

Answer:

Other than by writing separate oxidation and reduction reactions? Not to my knowledge...... And you asked a rather open-ended question.

Explanation:

This is best illustrated by an actual example. Chlorine gas is known to undergo disproportionation in alkaline conditions to give #"chloride"# and #"chlorate ions"#. This is the EXPERIMENTAL result, which must simply be known.

#"Reduction"#
#1/2Cl_2(g) + e^(-) rarr Cl^(-)# #(i)#

#"Oxidation"#
#1/2Cl_2(g) + 6HO^(-) rarr ClO_3^(-)+ 5e^(-) +3H_2O# #(ii)#

And #5xx(i) + (ii)# gives:

#3Cl_2(g) + 6HO^(-) rarr 5Cl^(-) + ClO_3^(-)+3H_2O#

Which is balanced with respect to mass and charge, as is always required. Clearly zerovalent chlorine gas has undergone reduction to chloride ion, and oxidation to chlorate ion; i.e. a disproportionation reaction.