Saturday, May 14, 2011

Electrochemical Cells

The example of electrochemical cell is Daniell cell, this cell structure was composed by Frederic Daniell, so the name of this cell is refer to that name, the British chemist who invented it in 1836.

The principle reaction occur on this cell is a galvanic or voltaic cell reaction that produce electricity. On the Daniell reaction there are reduction reaction and oxidation reaction, that apply on Zn (Zinc) and Cu (copper) materials. The reaction itself may be separated out so have an indirect transfer and can produce useable electricity.

Those galvanic cell are commonly called as batteries, but sometimes this name incorrect, because a battery is composed of two or more cells connected together.

The principle work on Daniel cell, piece of zinc is soaked in a solution of zinc sulfate in one container, and a piece of copper metal is soaked in copper sulfate and placed in other container. The plate of these metal are called as cell electrode.

If just connect this two electrode with wire there will nothing happens, but if you then put a salt bridge between two containers, then the electric effect will happen. The salt bridge provide a way for ions to move from one container to the other to keep the solutions electrically neutral. With the salt bridge in place, electrons can start to flow. Zinc is being oxidized, releasing electrons that flow through the wire to the copper electrode.

After the process run, copper electrode will covered with copper from copper sulfate solution, while zinc electrode will consumed and dissolved in zinc sulfate. The cations itself will transfer through the bridge. The electron from zinc will flow through the copper electrode through the salt bridge and give to the copper ion on the solution to be copper plated, because the electron is located on the copper surface electrode.