Igcse Model Questions Vol1 2019 Chemistry Question 16

Practice objective / multiple choice question 16 from the 2019 Igcse Model Questions Vol1 Chemistry examination.

Igcse Model Questions Vol1 2019 Chemistry Objective / Multiple Choice Hard Difficulty
Question 16 IGCSE_MODEL_QUESTIONS_VOL1 • 2019 • CHEMISTRY • objective

A metal oxide \(\mathrm{M_2O_3}\) is reduced to the metal \(\mathrm{M}\) by carbon at 1500 °C according to the reaction \(\mathrm{M_2O_3 + 3C \rightarrow 2M + 3CO}\). The standard enthalpy of formation of \(\mathrm{M_2O_3}\) is -800 kJ mol⁻¹, and the standard enthalpy of formation of CO(g) from C(s) and \(\tfrac{1}{2}\) O₂(g) is -110.5 kJ mol⁻¹. The molar entropy of CO(g) at 1500 °C is 197 J mol⁻¹ K⁻¹, while the reactants are solids with negligible gas entropy. Determine whether the reduction is thermodynamically feasible at 1500 °C. (Assume \(\Delta G \approx \Delta H - T\Delta S\).)

Answer Options

A. No; the reaction becomes spontaneous only above about 2.1×10³ K, which is higher than the furnace temperature of 1773 K.
B. No; ΔG remains positive at 1773 K, so the reduction is not thermodynamically feasible.
C. Yes; the reaction becomes spontaneous above about 5.0×10² K, and the furnace temperature of 1773 K satisfies this.
Correct Answer D. Yes; the reaction becomes spontaneous above about 7.9×10² K, and the furnace temperature of 1773 K satisfies this.
Correct Answer
D
Correct Option:
Yes; the reaction becomes spontaneous above about 7.9×10² K, and the furnace temperature of 1773 K satisfies this.

About This Question

This is Igcse Model Questions Vol1 2019 Chemistry Question 16. It is one of the objective questions from the 2019 Igcse Model Questions Vol1 Chemistry examination.

Difficulty level: Hard .

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