University:
Memorial University of Newfoundland
Course:
CHEM1050 | Laboratory
Academic year:

2020
Views:

320

Pages:

2
Author:

H. Mcqueen

Uses of Volta Cells In everyday life, the electric current produced from a chemical reaction in a voltaic cell has many uses, such as for radios, calculators, televisions, motor vehicles, etc. Voltaic cells in everyday life exist in the following forms. a. Battery Cells 1) Ordinary Batteries The batteries that we often use are also called dry cells or Lecanche cells. It is said to be a dry cell because the amount of water used is small (limited). This cell consists of: Anode: Zinc metal (Zn) which is used as a container. Cathode: Carbon rod (inactive). Electrolyte: A mixture in the form of a paste consisting of MnO2 , NH4 Cl, and a little water. Reaction: Anode : Zn(s) Zn2+(aq) + 2 e– Cathode: 2) Alkaline Batteries Alkaline batteries can produce twice as much energy as ordinary batteries. This cell consists of: Anode: Zinc metal (Zn), the same as batteries, is usually used as a container. Cathode: Manganese oxide (MnO2 ). Electrolyte: Potassium hydroxide (KOH). Reaction: Anode : Zn(s) Zn2+(aq) + 2 e– Cathode: 2 MnO2 + H2 O + 2 e– Mn2 O3 + 2 OH– Zn2+ ions react with OH– to form Zn(OH)2 . b. Cell battery Battery cells or batteries are an example of a voltaic cell that is reversible, where the reaction results can be converted back into the original substance. Battery cells can be recharged if they are weak, whereas battery cells cannot.This cell consists of: Anode: Lead metal plate (Pb). Cathode: Lead oxide metal plate (PbO2 ). Extrolyte: Dilute solution of sulfuric acid (H2 SO4 ). Battery discharge reaction: PbSO4 (s) + H+ (aq) + 2 e– Anode : Pb(s) + (aq) PbSO4 (aq) + 3 H+(aq) + 2 e– Cathode : PbO2 (s) (aq) + 3 H+(aq) + 2 e– PbSO4 (aq) + 2 H2 O Complete reaction: Pb(s) + PbO2 (s) + 2 (aq) + 2 H+ (aq) 2 PbSO4 (s) + 2 H2 O (l) When this cell produces an electric current, the Pb anode and PbO2 cathode change to form PbSO4 . The H+ ion from H2 SO4 changes to form H2 O so that the concentration of H2 SO4 will decrease. Then the battery cells can be charged/shocked again, so that the sulfuric acid concentration returns to normal. This process will be an example of an electrolysis cell.