Question

In the reaction $Mg+C{l}_2\to MgC{l}_2$:

• A. magnesium is oxidized and $C{l}_2$ is reduced
• B. magnesium is reduced and $C{l}_2$ is oxidized
• C. magnesium gains 2 electrons
• D. chlorine looses 1 electron

Answer 1

The correct option is A magnesium is oxidized and $C{l}_2$ is reduced

$\stackrel{0}{M}g+\stackrel{0}{C}{l}_2⟶MgC{l}_2$

Oxidation number of $Mg$ in $MgC{l}_2$: $x-2=0$

$\Rightarrow x=2$

Oxidaton number of $Cl$ in $MgC{l}_2$: $+2+2x=0$

$\Rightarrow 2x=-2$

$\Rightarrow x=-1$

So, $\stackrel{0}{M}g⟶\stackrel{+2}{M}g$ and $\stackrel{0}{C}{l}_2⟶\stackrel{-1}{C}l$

Therefore, magnesium is oxidised (increase in oxidation number) and $C{l}_2$ is reduced (decrease in oxidation number).