Use the chemical equation to complete the activity.
H2(g) + I2(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.
Iodine is in Group VIIA, so it has an oxidation number of –1 in both the reactant I2 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.