State the (i) electrolyte (ii) cathode used (iii) anode used (iv) electrode reaction at cathode (v) electrode reaction at anode (vi) product at cathode and anode

during

(a) electroplating an article with nickel (b) electroplating a spoon with silver (c) purification of impure copper.

(a) Electroplating an article with nickel :

1. Electrolyte — Aqueous solution of Nickle Sulphate
2. Cathode used — Cleaned article to be electroplated
3. Anode used — Active electrode. Plate or block of nickle metal
4. Electrode reaction at cathode — Ni²⁺ + 2e^- ⟶ Ni [deposited]
5. Electrode reaction at anode — Ni - 2e^- ⟶ Ni²⁺
6. Product at cathode — Nickel. (It is deposited on the article.)
   Product at anode — Nil (Ni²⁺ ions formed)

(b) Electroplating a spoon with silver :

1. Electrolyte — Sodium argentocyanide Na[Ag(CN)₂]
2. Cathode used — Cleaned article to be electroplated
3. Anode used — Active electrode. Plate or block of Silver metal
4. Electrode reaction at cathode — Ag¹⁺ + 1e^- ⟶ Ag [deposited]
5. Electrode reaction at anode — Ag - 1e^- ⟶ Ag¹⁺
6. Product at cathode — Silver. (It is deposited on the article.)
   Product at anode — Nil (Ag¹⁺ ions formed)

(c) Purification of impure copper :

1. Electrolyte — Aqueous copper sulphate solution [acidified]
2. Cathode used — Pure thin sheet of copper
3. Anode used — Impure block of copper
4. Electrode reaction at cathode — Cu²⁺ + 2e^- ⟶ Cu [deposited]
5. Electrode reaction at anode — Cu - 2e^- ⟶ Cu²⁺ [cation]
6. Product at cathode — Pure Copper. (It is deposited over thin sheet of pure Copper.)
   Product at anode — Nil (Cu²⁺ ions formed)