1. BANGABANDHU SHEIKH MUJIBUR RAHMAN SCIENCE AND TECHNOLOGY UNIVERSITY,GOPALGANJ Md.Habibur Rahman WELCOME TO MY PRESENTATION My presentation topic is- Usefulness of Ellingham diagram 2. What is Ellingham diagram? An Ellingham diagram is a graph showing the temperature dependence of the stability for compounds. This analysis is used to evaluate the ease of reduction of metal oxides and sulfides. First constructed by Harold Ellingham in 1944. In metallurgy, it is used to predict the equilibrium temperature between a metal, its oxide, and oxygen and by extension, reactions of a metal with sulfur, nitrogen, and other non- metals. 3. The Ellingham diagram Fig: Ellingham diagram for metals giving the free energy of formation of metal oxides and the corresponding oxygen partial pressure at equilibrium. 4. Ellingham diagrams are a particular graphical form of the principle of the thermodynamic feasibility of a reaction depends on the sign of ΔG, the Gibbs free energy change, which is equal to ΔH − TΔS, where ΔH is the enthalpy change and ΔS is the entropy change. Continue 5. Usefulness of “Ellingham diagram” The main application of Ellingham diagrams is in the extractive metallurgy industry The free energy change at equilibrium of formation of metal oxide from metal and O2 at any temp. can be directly determined from diagram. The Ellingham curve for aluminium lies below the curves of most metals such chromium, iron, etc. The free energies of formation of chromium(III) oxide and aluminium oxide per mole of oxygen consumed are -540kJ and -827kJ respectively. The processes are : The second equation minus the first equation gives So aluminium oxide is more stable than chromium oxide. Since the Gibbs free energy change is negative, aluminium can reduce chromium oxide. 6. Knowing the value of ΔG° at any temp. the partial pressure of O2 a metal oxide formation reaction can be calculated. Knowing the value of ΔG° the equilibrium const. of metal oxide formation reaction can be calculated. Entropy change of any metal oxide formation reaction can be known . At any temperature T, G is given by ΔG=ΔH-T.ΔS. Comparative stability of the metal oxide can be known. Height the line in Ellingham diagram indicates the instability Higher the line ,more positive ΔG ,the less formation of oxide. Continue 7. Continue Suitable reducing agent for any metal can be chosen. It also helps to select the best reducing agent for various ores in the extraction process, purification and grade setting for steel manufacturing. It also helps to guide the purification of metals, especially the removal of trace elements. The Ellingham diagram indicates that in this range carbon monoxide acts as a stronger reducing agent than carbon since the process 2CO+O2 → 2CO2 has a more-negative free energy change than the process 2C+O2 → 2CO. In the upper part of the blast furnace, haematite is reduced by CO in the presence of carbon. 8. Continue Reducing agent for chromic oxide: The Ellingham curve for the reaction 2C(s) + O2(g) →2CO(g) slopes down and falls below the curves for all the metals. Hence, carbon can normally act as a reducing agent for all metal oxides at very high temperatures. 9. THANKS EVERYBODY For listening my presentation with concentration.