The reaction of acetylene with hydrogen gas is shown below. Which statements are true concerning the reaction?
$$\mathrm{H}-\mathrm{C} \equiv \mathrm{C}-\mathrm{H}+2 \mathrm{H}_{2} \xrightarrow{\mathrm{Pd} \text { (cat.) }} \mathrm{H}_{3} \mathrm{C}-\mathrm{CH}_{3}$$
I. Acetylene is oxidized to ethane.
II. Acetylene is reduced to ethane.
III. Carbon changes oxidation state from -1 to -3 .
IV. Hydrogen (from $\mathrm{H}_{2}$ ) changes oxidation state from 0 to +1 .

Question

Quizplus · Accepted Answer

Acetylene is reduced to ethane because hydrogen is added to it. The oxidation state of carbon in acetylene (C2H2) changes from -1 in each carbon to -3 in ethane (C2H6), indicating reduction. Hydrogen's oxidation state does not change to +1 upon addition to a molecule; it remains at 0 in H2 and is considered -1 in hydrocarbons like ethane.

The Reaction of Acetylene with Hydrogen Gas Is Shown Below