Question

What chemical is oxidized in the following reaction? $Mg+2HCl\to MgC{{l}_{2}}+{{H}_{2}}$

Answer 1

Before answering this question, we should know The loss of electrons or increase in the oxidation number is the oxidation. Redox reactions are those reactions in which one atom is getting oxidized and the other atom is getting reduced.

Complete answer:
In the above reaction:
Magnesium metal $(Mg)$ is getting oxidized to magnesium cations$(M{{g}^{2+}})$-
$Mg(s)\to M{{g}^{2+}}+2{{e}^{-}}$
In the other case, Hydrogen is getting reduced from hydrogen ions (${{H}^{+}}$) to hydrogen gas (${{H}_{2}}$).
$2HCl\,+\,1{{e}^{-}}\to {{H}_{2}}$
We have to look at the oxidation states of the elements involved in the reaction.
$Mg+2HCl\to MgC{{l}_{2}}+{{H}_{2}}$
This equation is considered a redox reaction. The magnesium is getting oxidized to magnesium cations and hydrogen is getting reduced from hydrogen ions to hydrogen gas.
Here, The oxidation state of magnesium on the reactant side is 0 and on the product side, it becomes +2, which means it is getting oxidized.
The oxidation state of hydrogen on the reactant’s side is +1 and on the product’s side is 0, which means it is getting reduced.
This is why we can say Magnesium is behaving like a reducing agent as it reduces hydrogen ions to hydrogen gas and itself getting oxidized in the reaction whereas Hydrochloric acid acts as an oxidizing agent as it oxidizes magnesium to magnesium cations and itself getting reduced in the reaction.

Note:
Difference between oxidation and reduction are:
The loss of electrons from an atom or a molecule is known as oxidation whereas the gain of electrons from an atom or a molecule is known as Reduction. In oxidation, the oxidation state increases whereas in reduction, the oxidation state decreases. The release of electrons in the surrounding is Oxidation whereas the electrons obtained from the surrounding is reduction. The increase in the positive charge of a chemical species is caused by oxidation whereas the increase in the negative charge of a chemical species is caused by reduction. Oxidation happens in reducing agents whereas reduction happens in oxidizing agents. The two half-reactions of redox reactions are oxidation and reduction.