This presentation discusses the usefulness of Ellingham diagrams in metallurgy. An Ellingham diagram graphs the temperature dependence of metal oxide stability and is used to evaluate the ease of reducing metal oxides. It was first constructed by Harold Ellingham in 1944 and can predict equilibrium reactions between metals, oxygen, and other non-metals. Ellingham diagrams are useful for determining free energy changes and partial pressures of oxygen during metal oxide formation reactions. They allow metallurgists to select suitable reducing agents, guide purification processes, and understand the comparative stability of metal oxides.

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.