Thursday, July 25, 2013

Alessandro Volta: inventor of the electrochemical battery

Alessandro Giuseppe Antonio Anastasio Volta (18 February 1745 – 5 March 1827) was an Italian[1][2] physicist known for the invention of the battery in the 1800s.
In announcing his discovery of his voltaic pile, Volta paid tribute to the influences of William NicholsonTiberius Cavallo, andAbraham Bennet.[9]

Voltaic pile
The battery made by Volta is credited as the first electrochemical cell. It consists of two electrodes: one made of zinc, the other of copper. The electrolyte is either sulfuric acid mixed with water or a form of saltwater brine. The electrolyte exists in the form 2H+ and SO42−. The zinc, which is higher than both copper and hydrogen in the electrochemical series, reacts with the negatively charged sulfate (SO42−). The positively charged hydrogen ions (protons) capture electrons from the copper, forming bubbles of hydrogen gas, H2. This makes the zinc rod the negative electrode and the copper rod the positive electrode.
Thus, there are two terminals, and an electric current will flow if they are connected. The chemical reactions in this voltaic cell are as follows:
zinc
Zn  Zn2+ + 2e
sulfuric acid
2H+ + 2e  H2
The copper does not react, but rather it functions as an electrode for the electric current.
However, this cell also has some disadvantages. It is unsafe to handle, since sulfuric acid, even if dilute, is dangerous to human beings. Also, the power of the cell diminishes over time because the hydrogen gas is not released. Instead, it accumulates on the surface of the zinc electrode and forms a barrier between the metal and the electrolyte solution.