electrolysis


electrolysis
/i lek trol"euh sis, ee'lek-/, n.
1. Physical Chem. the passage of an electric current through an electrolyte with subsequent migration of positively and negatively charged ions to the negative and positive electrodes.
2. the destruction of hair roots, tumors, etc., by an electric current.
[1830-40; ELECTRO- + -LYSIS]

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Process in which electric current passed through a substance causes a chemical change, usually the gaining or losing of electrons (see oxidation-reduction).

It is carried out in an electrolytic cell consisting of separated positive and negative electrodes (anode and cathode, respectively) immersed in an electrolyte solution containing ions or in a molten ionic compound. Electric current enters through the cathode; positively charged cations travel to it and combine with electrons. Negatively charged anions give up electrons at the anode. Both thus become neutral molecules. Electrolysis is used extensively in metallurgy to extract or purify metals from ores or compounds and to deposit them from solution (electroplating). Electrolysis of molten sodium chloride yields metallic sodium and chlorine gas; that of a strong solution of sodium chloride in water (brine) yields hydrogen gas, chlorine gas, and sodium hydroxide (in solution); and that of water (with a low concentration of dissolved sodium chloride or other electrolyte) yields hydrogen and oxygen.

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      process by which electric current is passed through a substance to effect a chemical change. The chemical change is one in which the substance loses or gains an electron (oxidation or reduction). The process is carried out in an electrolytic cell (q.v.), an apparatus consisting of positive and negative electrodes (electrode) held apart and dipped into a solution containing positively and negatively charged ions. The substance to be transformed may form the electrode, may constitute the solution, or may be dissolved in the solution. Electric current (i.e., electrons (electron)) enters through the negatively charged electrode ( cathode); positively charged components of the solution travel to this electrode, combine with the electrons, and are transformed to neutral elements or molecules. The negatively charged components of the solution travel to the other electrode ( anode), give up their electrons, and are transformed into neutral elements or molecules. If the substance to be transformed is the electrode, the reaction is generally one in which the electrode dissolves by giving up electrons.

      Electrolysis is used extensively in metallurgical processes, such as in extraction (electrowinning) or purification (electrorefining) of metals from ores or compounds and in deposition of metals from solution (electroplating). Metallic sodium and chlorine gas are produced by the electrolysis of molten sodium chloride; electrolysis of an aqueous solution of sodium chloride yields sodium hydroxide and chlorine gas. Hydrogen and oxygen are produced by the electrolysis of water.

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Universalium. 2010.

Look at other dictionaries:

  • Electrolysis — E lec*trol y*sis, n. [Electro + Gr. ? a loosing, dissolving, fr. ? to loose, dissolve.] (Physics & Chem.) The act or process of chemical decomposition, by the action of electricity; as, the electrolysis of silver or nickel for plating; the… …   The Collaborative International Dictionary of English

  • Electrolysis — Electrolysis. См. Электролиз. (Источник: «Металлы и сплавы. Справочник.» Под редакцией Ю.П. Солнцева; НПО Профессионал , НПО Мир и семья ; Санкт Петербург, 2003 г.) …   Словарь металлургических терминов

  • electrolysis — (n.) 1834, introduced by Faraday on the suggestion of the Rev. William Whewell (1794 1866), English polymath, from ELECTRO (Cf. electro ) + Gk. lysis a loosening, from lyein to loosen, set free (see LOSE (Cf. lose)). Originally of tumors, later… …   Etymology dictionary

  • electrolysis — ► NOUN 1) chemical decomposition produced by passing an electric current through a conducting liquid. 2) the breaking up and removal of hair roots or small blemishes on the skin by means of an electric current. DERIVATIVES electrolytic adjective …   English terms dictionary

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  • Electrolysis — In chemistry and manufacturing, electrolysis is a method of separating chemically bonded elements and compounds by passing an electric current through them.History*1800 William Nicholson and Johann Ritter decomposed water into hydrogen and oxygen …   Wikipedia

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  • electrolysis — [[t]ɪlektrɒ̱lɪsɪs, i͟ː [/t]] N UNCOUNT Electrolysis is the process of passing an electric current through a substance in order to produce chemical changes in the substance. [TECHNICAL] …   English dictionary

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  • electrolysis —   n. decomposition of substance by elec. current.    ♦ electrolyse, v.t.    ♦ electrolyte, n. substance, especially dissolved in liquid, which is separated by current in electrolysis.    ♦ electrolytic, a …   Dictionary of difficult words


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