History on PowerPoint: Electrochemistry. David A. Katz Department of Chemistry Pima Community College – West Campus 2202 W. Anklam Rd Tucson, AZ 85709 USA Email: [email protected] A History of Electricity/Electrochemistry.
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Thales of Miletus
Otto von Guericke
A voltaic pile consist of alternating layers of two dissimilar metals, separated by pieces of cardboard soaked in a sodium chloride solution or sulfuric acid.
Volta determined that the best combination of metals was zinc and silver
Volta’s electric pile (right)
A Voltaic pile at the Smithsonian Institution, (far right)
Johann Wilhelm Ritter
The amount of a substance deposited on each electrode of an electrolytic cell is directly proportional to the amount of electricity passing through the cell.
The quantities of different elements deposited by a given amount of electricity are in the ratio of their chemical equivalent weights.
The anode is therefore that surface at which the electric current, according to our present expression, enters: it is the negative extremity of the decomposing body; is where oxygen, chlorine, acids, etc., are evolved; and is against or opposite the positive electrode.
The cathode is that surface at which the current leaves the decomposing body, and is its positive extremity; the combustible bodies, metals, alkalies, and bases are evolved there, and it is in contact with the negative electrode.
Many bodies are decomposed directly by the electric current, their elements being set free; these I propose to call electrolytes....
Finally, I require a term to express those bodies which can pass to the electrodes, or, as they are usually called, the poles. Substances are frequently spoken of as being electro-negative or electro-positive, according as they go under the supposed influence of a direct attraction to the positive or negative pole...I propose to distinguish such bodies by calling those anions which go to the anode of the decomposing body; and those passing to the cathode, cations; and when I have occasion to speak of these together, I shall call them ions.
…the chloride of lead is an electrolyte, and when electrolyzed evolves the two ions, chlorine and lead, the former being an anion, and the latter a cation.
Left: An early Daniell Cell
Right:Daniell cells used by Sir William Robert Grove, 1839.