Chapter U5, Problem 13RE

Interpretation Introduction

Interpretation: From net ionic equations, reactant atoms that are oxidized and cations that are reduced in given chemical equations needs to be shown.

Concept introduction: Chemical equation is the symbolic description of a chemical reaction that products and reactants are indicating in terms of their chemical formula.

Answer to Problem 13RE

Given chemical equation is as follows:

  $\text{Zn}\left(s\right)+2{\text{MnO}}_{\text{2}}\left(s\right)\to \text{ZnO}\left(s\right)+{\text{Mn}}_2{\text{O}}_{\text{3}}\left(s\right)$

In above equation Zn loses electrons and ${\text{Mn}}^{\text{4+}}$ gains electrons. Thus Zn is oxidize and ${\text{Mn}}^{\text{4+}}$ reduces.

Given chemical equation is as follows:

  $3\text{CaO}\left(s\right)+2\text{Al}\left(s\right)\to {\text{Al}}_{\text{2}}{\text{O}}_3\left(s\right)+3\text{Ca}\left(s\right)$

In above equation aluminum loses electrons and calcium gains electrons. Thus Al is oxidize and Ca reduces.

Explanation of Solution

Given chemical equation is as follows:

  $\text{Zn}\left(s\right)+2{\text{MnO}}_{\text{2}}\left(s\right)\to \text{ZnO}\left(s\right)+{\text{Mn}}_2{\text{O}}_{\text{3}}\left(s\right)$

Overall ionic equation is as follows:

  $\text{Zn}\left(s\right)+2{\text{Mn}}^{\text{4+}}\left(aq\right)\to {\text{Zn}}^{\text{2+}}\left(aq\right)+2{\text{Mn}}^{\text{3+}}\left(aq\right)$

In above equation Zn loses electrons and ${\text{Mn}}^{\text{4+}}$ gains electrons. Thus Zn is oxidize and ${\text{Mn}}^{\text{4+}}$ reduces.

Given chemical equation is as follows:

  $3\text{CaO}\left(s\right)+2\text{Al}\left(s\right)\to {\text{Al}}_{\text{2}}{\text{O}}_3\left(s\right)+3\text{Ca}\left(s\right)$

Overall ionic equation is as follows:

  $3{\text{Ca}}^{\text{2+}}\left(s\right)+2\text{Al}\left(s\right)\to 2{\text{Al}}^{\text{3+}}\left(s\right)+3\text{Ca}\left(s\right)$

In above equation aluminum loses electrons and calcium gains electrons. Thus Al is oxidize and Ca reduces.

Conclusion

In a redox reaction an atom or ion gains electrons and another atom or ion loses electrons. Oxidation is loss of electrons, and reduction is gain of electrons.