Oh not prof. vitarelli spots sybil running down the yelling something about her tea prof. vitarelli and prof. snape try to hold her back. but they fail. she yells, i’ve learned another exam question from last year! zinc metal reacts with hydrochloric acid to produce hydrogen gas and an aqueous solution of zinc(ii) chloride. what is the reducing agent in this reaction? maybe prof. umbridge was right in trying to remove her.

The reducing agent is Zn.

Explanation:

Let's consider the reaction between zinc and hydrochloric acid.

Zn(s) + 2 HCl(aq) ⇄ ZnCl₂(aq) + H₂(g)

This is a redox reaction, which can be divided in 2 half-reactions: reduction and oxidation.

In the reduction, H⁺ gains electrons and it is considered the oxidizing agent.

2H⁺ + 2 e⁻ ⇒ H₂

In the oxidation, Zn loses electrons and it is considered the reducing agent.

Zn ⇒ Zn²⁺ + 2 e⁻

  the   balanced   equation   for   reaction of   ca metal   with   o2 to   produce   cao   is as below

2 ca+ o2→ 2 cao2

  explanation

the reaction is   balanced     since the   number of atoms   in reactant side is   equal to   number of atoms   in   product side.   for   example   they   are 2   atom of   ca in   reactant   side   and   2   atoms of ca   in   the product side.

  the   process   is a   meet the   requirement   of   redox   reaction because :     calcium   is   oxidized   from   oxidation state 0   to 2+   while   oxygen   is reduced from   oxidation   state   0   to 2-