An Ellingham diagram is a graph showing the temperature dependence of the stability of compounds. The metal oxide is mixed with carbon and heated in a furnace.Carbon reduces metal oxide to free metal. The reduction of metals was originally understood to be the reactions used to obtain metals from their oxides by using substances having greater affinity for oxygen than the metal. Since the majority of ores are oxides or can be converted to oxides by roasting, the free-energy change accompanying the decomposition of the oxide forms a convenient measure of how readily a metal may be obtained from its ore. These metals are placed at the bottom of the electrochemical series. For reduction, different types of reducing agents are used depending on reactivity of ores. Reduction of metal halides with metals In many cases, carbon cannot be used to reduce the metal oxide to the metal as the metal reacts with carbon to form the carbide instead. Several dopant conditions were used, to find the effect on oxide structures and reaction kinetics of the usual dopants K, Si and Al. Tungsten oxide, WO2.96, was reduced toα-W in hydrogen for various time periods over the temperature range 500°C to 900°C. Furthermore, the direct reduction technique consistently produces high purity (98%–99% pure) neptunium metal. Reduction of Iron; Contributors; The ease with which a metal may be obtained from its ore varies considerably from one metal to another. Reduction of Metal Oxides to Free Metal Heating – Less reactive metals like silver and mercury can be obtained by heating their oxides alone. It is possible to avoid this problem by first converting the ore to the chloride, and then reducing the chloride with a more reactive metal such as magnesium or sodium. After reduction of the oxide to metal, the metal is separated by density from the other components of the reaction mixture and can easily removed upon cooling. REDUCTION OF METAL OXIDE TO METAL The process of converting metal oxides into metals is called reduction. Recent work has demonstrated that solid metal oxides can be directly electro-reduced to the respective metals or alloys in molten salts. The commonly used methods for reduction are : 1. For the reduction of metal oxide, the Gibbs energy should be negative. At the higher temperatures, the reduction of the metal oxide is easier. In solid state, the entropy or randomness will be less due to high intermolecular force of attraction while in liquid state, the entropy will be more comparatively. This analysis is usually used to evaluate the ease of reduction of metal oxides and sulfides.These diagrams were first constructed by Harold Ellingham in 1944. Intermediate oxides were determined using X-ray diffraction analysis of the semireduced powders. Here we use 2D magnesium oxide (MgO) overlayers on metal substrates for electrocatalysis of CO 2 reduction. 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