Question

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.

Answer 1

This problem is providing statements whereby an student is pretending to explain a wrongly-classified non-redox reaction via the change in the oxidation numbers the elements undergo as it takes place. It is asked to report where the student went wrong and to determine whether the reaction is redox or not.

In such a way, we can start by saying that the student was right about the +1 on H and -1 on I but just on HI, not on the diatomic gases too, because when the elements act alone in a chemical equation, their oxidation states must be 0 as they are not forming any ions.

Next, we can go over the identification of the reaction as redox, by writing the correct oxidation numbers in the considered chemical equation:

$I_2^0(g)+H_2^0(g)\rightleftharpoons 2H^+I^-(g)$

Which exhibits an oxidation half-reaction for hydrogen because it changed from 0 to +1 and a reduction half-reaction for iodine because it changed from 0 to -1, and thus, when the oxidation numbers change, we say the reaction is redox.

Learn more:

• (Balancing redox) https://brainly.com/question/8344408