Different Types of Electrochemical Cells
Different types of electrochemical cells are used for different purposes. Fuel cells, Daniel cells and dry cells are three types of cells and they have different characteristics in their physical appearance and working conditions.
Following types of electrochemical cells are covered in this tutorial.
- Fuel cells
- Daniel cells
- Dry cells
Fuel cells
Fuel cells can convert chemical energy to electrical energy. Fuel is supplied to one electrode and oxidant (O2) to the other electrode.
Ex: Hydrogen /Oxygen fuel cell
Hydrogen /Oxygen fuel cell
Astronauts use the products of this reaction to supplement their drinking water.
At the electrodes of the above cell,
Anode reaction;
1/2H2(g) + OH-(aq) → H2O(l) + e
Cathode reaction;
1/2O2(g) + H2O(l) + 2e → 2OH-(aq)
Overall reaction in fuel cell;
2H2(g) + O2(g) → 2H2O(l)
Daniel cell
Daniel cell is a general type of cell which could be categorized as a metal/metal ion cell. Electromotive force of a Daniel cell depends
upon the individual cell potentials. In Daniel cells, a solution junction or a salt bridge is used to separate the individual electrodes.
Daniel cell contains Zn and Cu electrodes. Electrolyte solution is aqueous ZnSO4 and CuSO4.
Dry cell
In dry cells, no liquid or aqueous electrolytes are used. A Graphite rod connects the positive brass plate and the negative zinc plate. Electrolyte is made using starch and NH4Cl.
At the electrodes of the above cell,
Anode reaction;
Zn(s) → Zn2+(aq) + 2e
Cathode reaction;
2NH4+(aq) + 2e → 2NH3(g) + H2(g)
In dry cells the electrolyte should be made into a paste.
Lead acid battery
6,2V cells connected in a series. Each consists of two lead plates dipping in a 30% of H2SO4 solution. One plate is coated with PbO2 and the other plate is pure Pb. We have two plates in lead acid battery Lead plate functions as the anode while the PbO2 plate functions as the cathode.
Anode reaction;
Pb(s) + SO42-(aq) → PbSO4(s) + 2e
Cathode reaction;
PbO2(s) + 4H+(aq) + SO42-(aq) + 2e → PbSO4(s) + H2O
Questions
