Which of the following acts as a reductant in the reaction: H_2(g) + Cl_2(g) → 2HCl(g)?

• A. H_2(g)
• B. HCl(g)
• C. Cl_2(g)

Answer: (A)

Verified step by step guidance

1. Identify the species involved in the reaction: H_2(g), Cl_2(g), and HCl(g).
2. Recall that a reductant (reducing agent) is the species that donates electrons and gets oxidized in the reaction.
3. Determine the oxidation states of hydrogen and chlorine in the reactants and products. In H_2(g), hydrogen has an oxidation state of 0; in Cl_2(g), chlorine has an oxidation state of 0; in HCl(g), hydrogen is +1 and chlorine is -1.
4. Compare the oxidation states from reactants to products to see which species is oxidized (increase in oxidation state) and which is reduced (decrease in oxidation state).
5. Conclude that the species whose oxidation state increases is the reductant, so identify H_2(g) as the reductant because hydrogen goes from 0 to +1.