writing the half reactions

Question

Ca (s) + ZnCl2 (aq) --> Zn (s) + CaCl2 (aq)

Then, write balanced half-reactions describing the oxidation and reduction that happen in this reaction.

Answer 1

Ca (s) + ZnCl₂ (aq) --> Zn (s) + CaCl₂ (aq)

Look at the oxidation numbers of each element on the left and right side of the reaction.

Ca on the left is zero. Ca on the right is 2+. Ca has lost 2 electrons so Ca has been oxidized

Zn on the left is 2+. Zn on the right is zero. Zn has gained 2 electrons so Zn has been reduced

Writing the 2 half reactions, we have ...

Ca(s) ==> Ca²⁺(aq) + 2e- ... oxidation half reaction

Zn²⁺(aq) +2e- ==> Zn(s) ... reduction half reaction