At the turn of the 18th and 19th centuries were made several discoveries that became the impetus for the birth of a new science - electrochemistry.And the founders of this science were two scientists.It is an Italian physiologist Luigi Galvani and A. Volta the English physicist, who in 1799 created the first chemical current source - "Voltaic pile."That's what researchers found out that when an electric current is passed through an aqueous solution of any salt in this solution, a chemical transformation that is now called the electrolyte.Electrolysis itself is a rather complicated set of different processes.This migration (negative ions tend to the anode and the cathode are positive), and the diffusion of ions.This also various electrochemical and chemical reactions that occur between themselves products of electrolysis between these products and the electrolyte, and the electrodes therebetween.
A study of these processes has not only scientific value.Practical application of electrolysis is very important.For example, pure hydrogen, sodium, or nickel can be obtained only in this way.And industrial electrolytic processes are used for various purposes.With their help obtain inorganic substances, such as oxygen, hydrogen, alkali, chlorine and other non-metals.Also, the electrolysis used for cleaning certain metals (silver, copper).Another electrolytic processes form the basis for preparation of lithium, potassium, sodium, zinc, magnesium and other metals and metal alloys.
Besides the use of electrolysis in the art - it is also the preparation of organic compounds, electroplating and surface treatment of metal (electropolishing, boriding, treatment and nitriding).There are electrophoresis, electrodialysis, electroplating and other similar processes, with practical application.Also worth electrolysis is that it can get a clean, almost entirely metals.
take at least copper.The copper ore it contains oxides, sulfur compounds, as well as impurities of other metals.And copper obtained from this ore, with all of these impurities is cast in plates.Then the plates are placed as the anode in a solution of copper sulfate (CuSO4).And followed by the use of electrolysis.In the bath electrodes is fed a certain voltage on the cathode and pure metal stands.And all impurities are precipitated or pass into the electrolyte, without standing on the cathode.
also use electrolysis true for aluminum production.The aqueous solution in this process is not applied, it is replaced with the molten bauxite.In such ores contain aluminum oxide and iron oxide and silica.After treatment of bauxite with alkali to give the product, called alumina.This alumina is loaded into a refractory furnace at the bottom and sides lined with carbon which plate.These plates are connected to the negative power supply.A positive terminal is connected to the carbon anode that extends through the wall of the furnace.And when lowering the anode furnace in an electric arc melts the alumina.Later in this molten mass occurs electrolytic process.And on the bottom of the furnace accumulates pure (99.5%) aluminum which is then poured into molds.
But the use of electrolysis is not only electrometallurgy.In this way, one can cover the metal layer of another metal.This process is called electroplating and applies it in order to prevent the metal surface from oxidation, giving it greater strength and to impart this desired surface appearance.And as coatings generally used nickel and chrome, are little susceptible to oxidation or noble metals such as silver and gold.
In this case, the article to be plated carefully degreased, cleaned and polished.Then it was placed as the cathode in the plating bath.The electrolyte in the bath is a metal salt solution, which will be covered by the product.And the anode is made of the same metal.And it is to obtain uniform coating, the cathode is sandwiched between two anodes.Then the electrodes supplied with a current of a certain power, and the cathode is covered with a layer of silver, gold, nickel or chromium.
There are such use electrolysis, which is called electroformed.This method provides copies of various metallic objects (medals, coins, bas-reliefs).To do this, a plastic material, such as wax, is a copy of the object.Then it was coated with graphite dust to give it electroconductivity and the copy is placed in the bath, where it serves as a cathode.And the copy by electrolysis of metal covered with a layer of desired thickness.A wax is then removed by heating.And this is only a small part of the opportunities offered by a method called electrolysis.
