# Is the dissolution of a solid metal in an acidic solution an example of a "redox reaction?"

Jan 3, 2017

$Z n \left(s\right) + 2 H C l \left(a q\right) \rightarrow Z n C {l}_{2} \left(a q\right) + {H}_{2} \left(g\right) \uparrow$

## For the oxidation of $\text{Zn}$:

$Z n \left(s\right) \rightarrow Z {n}^{2 +} + 2 {e}^{-}$; $\text{oxidation (i)}$

## For the reduction of $\text{hydronium ion}$:

${H}^{+} + {e}^{-} \rightarrow \frac{1}{2} {H}_{2} \left(g\right)$; $\text{reduction (ii)}$

We add these equations together such that electrons do not appear in the equation: $\left(i\right) + 2 \times \left(i i\right) :$

$Z n \left(s\right) + 2 {H}^{+} \rightarrow Z {n}^{2 +} + {H}_{2} \left(g\right) \uparrow$

We would repeat this for iron metal and sulfuric acid, except that sulfuric acid is a non-oxidizing acid under normal circumstances, and the question SHOULD have been asked with respect to hydrochloric acid or nitric acid. Iron filings will react with $H C l$ in precisely the same stoichiometry as zinc:

$F e \left(s\right) + 2 H C l \left(a q\right) \rightarrow F e C {l}_{2} \left(a q\right) + {H}_{2} \left(g\right) \uparrow$