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.
1 answer
The student made a mistake in assuming that the oxidation number of hydrogen and iodine remain the same throughout the reaction. In the reactant H2, hydrogen has an oxidation number of +1, while in the product HI, hydrogen has an oxidation number of 0. Similarly, in the reactant I2, iodine has an oxidation number of -1, while in the product HI, iodine has an oxidation number of -2. This change in oxidation number indicates that the reaction is a redox reaction.
2 answers