Alessandro Volta

     Alessandro Antonio Volta (1745 - !827), on Italian physicist, invented the electric battery which provided the first continous flow of electric and the capacitor. Born into a noble family in Como, Italy, Volta was performing electrical experiments at age 18. His invention of the battery in 1796 revolutionized the use of electricity. The publication of his work in 1800 marked the beginning of electrical cicuit thory. Volta received many honors during his liftime. The unit of voltage or potential difference, the Volt, was named in his honor.

First Battery

In announcing his discovery of the pile, Volta paid tribute to the influences of William Nicholson, Tiberius Cavallo and Abraham Bennet.

An additional invention pioneered by Volta, was the remotely operated pistol. He made use of a Leyden jar to send an electric current from Como to Milan (~50 km or ~30 miles), which in turn, set off the pistol. The current was sent along a wire that was insulated from the ground by wooden boards. This invention was a significant forerunner of the idea of the telegraph which also makes use of a current to communicate.

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 sulfuric acid or a brine mixture of salt and water. The electrolyte exists in the form 2H⁺ and SO₄^2-. The zinc, which is higher than both copper and hydrogen in the electrochemical series, reacts with the negatively charged sulfate (SO₄^2-). 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.

We now have two terminals, and the current will flow if we connect them. The reactions in this cell are as follows:

zinc

Zn → Zn²⁺ + 2e^-

sulfuric acid

2H⁺ + 2e^- → H₂

The copper does not react, functioning as an electrode for the chemical reaction.

However, this cell also has some disadvantages. It is unsafe to handle, as sulfuric acid, even if dilute, is dangerous. Also, the power of the cell diminishes over time because the hydrogen gas is not released, accumulating instead on the surface of the zinc electrode and forming a barrier between the metal and the electrolyte solution.

The primitive cell is widely used in schools to demonstrate the laws of electricity and is known as the lemon battery.