H2(g) + 12(g) - 2HI(g)
A student makes the following statements:
Hydrogen always has the same oxidation number, so it has an oxidation number of +1 in both the reactant H2 and
product HI.
lodine is in it Group VIIA, so it has an oxidation number of -1 in both the reactant l2 and product HI.
Neither hydrogen nor iodine changes oxidation states,
so the reaction is not a redox reaction.
In three to five sentences, describe the mistake that the student made, and determine whether or not the reaction is a redox
reaction. Explain your answer.