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NEET Questions / Chemistry / General Principles And Processes Of Isolation Of Elements
Consider the Ellingham diagram. Which metal oxide among the following can be reduced by coke at a temperature of 1500 K but not at 1200 K?
MgO
AlβOβ
ZnO
FeO
The Ellingham diagram for the formation of metal oxides shows a sudden increase in the slope for some metals. This is primarily due to:
Melting of the metal
Boiling of the metal
Phase transition of the metal
Formation of a non-stoichiometric oxide
Which of the following statements is INCORRECT regarding the Ellingham diagram?
The Ellingham diagram plots Gibbs free energy change as a function of temperature.
The Ellingham diagram assumes all reactants and products are in their standard states.
The Ellingham diagram can be used to determine the rate of a reaction.
The slope of the lines in the Ellingham diagram is determined by the entropy change of the reaction.
Why does the vs. T curve for the formation of from have a negative slope in the Ellingham diagram?
Increase in entropy due to increase in gaseous moles.
Decrease in entropy due to decrease in gaseous moles.
Constant entropy as gaseous moles remain the same.
The reaction is exothermic.
Given the Ellingham diagram, predict the minimum temperature at which magnesium can reduce to Si.
1500 K
1850 K
2000 K
2200 K
The Ellingham diagram does NOT directly account for which of the following factors that can influence the feasibility of a reduction reaction?
Temperature
Partial pressure of gases involved
Kinetics of the reaction
Entropy change of the reaction
The Ellingham diagram suggests that the reduction of alumina () by magnesium (Mg) is feasible. Which of the following statements best explains this feasibility?
The Gibbs free energy change for the overall reaction is positive.
The enthalpy change for the reaction is positive.
The entropy change for the reaction is negative.
The Gibbs free energy change for the overall reaction is negative.
