Chapter 18, Problem 21A

Interpretation Introduction

Interpretation: The element that is oxidized and reduced to be identified from given reaction.

$\text{Mg}\left(s\right)+2{\text{H}}_{\text{2}}\text{O}\left(g\right)\to \text{Mg}{\left(\text{OH}\right)}_{\text{2}}\left(s\right)+{\text{H}}_{\text{2}}\left(g\right)$

Concept introduction: Oxidation state is the concept which confesses to keep the path of electrons in oxidation−reduction reactions.

Answer to Problem 21A

Magnesium is oxidized and hydrogen is reduced.

Explanation of Solution

The given reaction is as follows:

$\text{Mg}\left(s\right)+2{\text{H}}_{\text{2}}\text{O}\left(g\right)\to \text{Mg}{\left(\text{OH}\right)}_{\text{2}}\left(s\right)+{\text{H}}_{\text{2}}\left(g\right)$

For above reaction, magnesium is oxidized because oxidation state of magnesium increases from 0 to +2. Hydrogen is reduced because oxidation state of hydrogen decreases from +1 to 0.

Conclusion

Oxidation − reduction reaction is a chemical reaction which associates transfer of electrons.