Clark cell

Clark Cell is a type of electrochemical cell named after its inventor, Josiah Latimer Clark. It was first developed in the 19th century and is used as a standard of electromotive force (EMF).

History

The Clark Cell was invented by Josiah Latimer Clark in 1872. Clark was an English electrical engineer who made significant contributions to the development of telegraphy and electrical power distribution. The Clark Cell was one of his most notable inventions, providing a reliable and stable reference for electromotive force.

Design and Operation

The Clark Cell consists of a zinc electrode immersed in a solution of zinc sulfate, and a mercury electrode covered with a layer of mercurous sulfate, both separated by a potassium sulfate solution. The cell operates at a temperature of 15 degrees Celsius and generates a potential of approximately 1.434 volts.

The chemical reaction that occurs within the cell can be represented as follows:

Zn + Hg2SO4 → ZnSO4 + 2Hg

This reaction is reversible, which allows the cell to maintain a constant electromotive force over time.

Applications

The Clark Cell was widely used as a standard of electromotive force until the mid-20th century. It was particularly useful in the calibration of voltmeters and other electrical measuring instruments. Today, it has largely been replaced by more modern standards, but it remains an important historical reference in the field of electrochemistry.

See Also

• Electrochemical cell
• Josiah Latimer Clark
• Electromotive force
• Zinc
• Mercury
• Chemical reaction