Question

(a) A solution of silver nitrate is a good electrolyte but it is not used for electroplating an article with silver.
(b) Identify the following reactions as either oxidation or reduction:
(i) O + 2e⁻ $\stackrel{}{\to }$ O²⁻
(ii) K − e⁻ $\stackrel{}{\to }$ K⁺
(iii) Fe³⁺ + e⁻ $\stackrel{}{\to }$ Fe²⁺

Answer 1

(a) Even though a solution of silver nitrate is a good electrolyte, it is not used for electroplating an article with silver because with silver nitrate, the deposition of silver on the articles takes place at a high speed, that results in rough and uneven plating.

(b) (i) $\mathrm{O}+2{\mathrm{e}}^{-}\stackrel{}{\to }{\mathrm{O}}^{2-}$
This is a reduction reaction. Here, the oxygen atom gains two electrons and gets reduced to oxide ion.

(ii) $\mathrm{K}-{\mathrm{e}}^{-}\stackrel{}{\to }{\mathrm{K}}^{+}$
This is an oxidation reaction. Here, potassium metal loses one electron and gets oxidised to potassium ion.

(iii) ${\mathrm{Fe}}^{3+}+{\mathrm{e}}^{-}\stackrel{}{\to }{\mathrm{Fe}}^{2+}$.
This is a reduction reaction. Here, iron (III) or ferric ions gain an electron and get reduced to iron (II) or ferrous ions.