Taken these reactions:

\begin{align} \ce{2\overset{0}{Fe} + 3Cl2 &-> 2\overset{+3}{Fe}Cl3} \tag{1}\\ \ce{\overset{0}{Fe} + 2HCl &-> \overset{+2}{Fe}Cl2 + H2} \tag{2} \end{align}

Why does $\ce{Fe}$ have +3 charge in the first example and +2 charge in the second?


Iron exists in the +2 oxidation state (iron(II)), also called ferrous iron, as well as the +3 oxidation state (iron(III)), also called ferric iron. There are sever other oxidation states of iron that are not pertinent to your reactions.

In your first reaction, the strongly oxidizing $\ce{Cl}$2 oxidizes the neutral, metallic iron to it's highest stable oxidation state, iron(III).

In your second reaction, $\ce{HCl}$ oxidizes iron to the lower stable oxidation state, iron(II).

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