Question

What are the oxidation numbers of the atoms in this reaction?

Answer 1

Answer : The correct options are:

0 for Mg(s) and H in $H_2$

+1 for H in HCl

+1 for H in HCl

+2 for Mg in $MgCl_2$

Explanation :

The given chemical reaction is:

$Mg(s)+2HCl(aq)\rightarrow MgCl_2(aq)+H_2(g)$

Oxidation state of Mg(s) is, 0

Oxidation state of hydrogen in HCl is, (+1)

Oxidation state of chlorine in HCl is, (-1)

Oxidation state of Mg in $MgCl_2$ is, (+2)

Oxidation state of Cl in $MgCl_2$ is, (-1)

Oxidation state of hydrogen in $H_2$ is, 0

The given reaction is a single displacement reaction in which the most reactive metal (Mg) displaces the least reactive element (H) from its compound.

It is also a redox reaction because the oxidation state of Mg changes from 0 to (+2) and shows oxidation and the oxidation state of hydrogen changes from (+1) to 0 and shows reduction.

Answer 2

all these are correct:
0 for Mg(s) and H in H2

+1 for H in HCl

-1 for Cl in HCl

+2 for Mg in MgCl2

only the first statement is wrong