Login or Sign Up
Menu
Ask a New Question

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.

The student made a mistake in saying that the reaction is not a redox reaction. Although hydrogen and iodine do not change oxidation states, the reaction is still a redox reaction because the oxidation states of the reactants and products are different. The oxidation number of hydrogen changes from +1 in the reactant H2 to +1 in the product HI, and the oxidation number of iodine changes from -1 in the reactant I2 to -1 in the product HI. Therefore, the reaction is a redox reaction.