The student incorrectly stated that hydrogen has an oxidation number of +1 in H2 and HI. In the molecular form H2, hydrogen has an oxidation number of 0 because it is in its elemental state. While it does have an oxidation number of +1 in HI, this indicates that hydrogen undergoes an oxidation state change during the reaction. The student also misinterpreted iodine's oxidation state; in the elemental form I2, iodine has an oxidation number of 0, not -1, which is its oxidation state in HI. Since both hydrogen and iodine change their oxidation states from 0 to +1 and 0 to -1, respectively, this reaction is indeed a redox reaction.
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 3–5 sentences, describe the mistakes that the student made. Based on the oxidation numbers, is this a redox reaction? Explain your answer.
1 answer