JEE Main · 2020 · 06 Sep 2020 · Shift 2 · Chemical Thermodynamics

For a reaction,

4 M (s) + nO_{2} (g) \to 2 M_{2} O_{n} (s)

,
the free energy change is plotted as a function of temperature. The temperature below which the oxide is stable could be inferred from the plot as the point at which

(A)the slope changes from negative to positive.
(B)the free energy change shows a change from negative to positive value.✓ Correct
(C)the slope changes from positive to negative.
(D)the slope changes from positive to zero.

Answer: (B)

Solution

On an Ellingham-type plot of

Δ G

against temperature, the oxide is thermodynamically stable only while the free energy of its formation stays negative. The temperature below which the oxide is stable is therefore the point at which

Δ G

crosses zero, changing from a negative to a positive value.

JEE Main · 2020 · 06 Sep 2020 · Shift 2 · Single correct option

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JEE Main · 2020 · 06 Sep 2020 · Shift 2 · Chemical Thermodynamics

Solution

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