Which reaction is favored at low pressure?
Correct answer: C. PCl₅ ⇌ PCl₃ + Cl₂
- A. N₂ + 3H₂ ⇌ 2NH₃
- B. N₂ + O₂ ⇌ 2NO
- C. PCl₅ ⇌ PCl₃ + Cl₂
- D. H₂ + F₂ ⇌ 2HF
Explanation
According to Le Chatelier's principle, decreasing the pressure shifts the equilibrium to the side with a greater number of moles of gas. In this reaction, 1 mole of gas decomposes into 2 moles of gas, so it is favored by low pressure.
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About Chemical Equilibrium
Reversible reactions reach dynamic equilibrium when forward and reverse rates become equal, and Le Chatelier's principle predicts the effect of changing concentration, pressure or temperature. The chapter also covers solubility product, the common ion effect, buffer action and the conditions used in Haber's process, with equilibrium shifts distinguished from changes in the equilibrium constant.
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