For the reaction PCl₅ (g)⇌ PCl₃ (g)+ Cl₂ (g),K_c = 0.0454 at 261 °C.If a vessel is filled with theses gases such that the initial concentrations are [PCl₅] = 0.2 M,[PCl₃] = 0.2 M,and [Cl₂] = 2.25 M,which of the following statements is TRUE? A)the reaction is at equilibrium B)the forward reaction is spontaneous C)the reverse reaction is spontaneous D)the forward reaction is exothermic E)the reverse reaction is exothermic

Question

Quizplus · Accepted Answer

We can examine the reaction quotient Qc to determine whether the reaction has reached equilibrium or not. Using the initial concentrations given, we can calculate Qc:

Qc = [PCl3][Cl2] / [PCl5] 
= (0.2 M)(2.25 M) / (0.2 M)^2 
= 2.25

Since Qc is greater than the equilibrium constant Kc, the reaction will shift towards the products to reach equilibrium. Therefore, the reverse reaction is spontaneous (choice C) while the forward reaction is not spontaneous. We cannot determine whether the forward reaction is exothermic or endothermic from the information given.

For the Reaction PCl5 (G)⇌ PCl3 (G)+ Cl2 (G),Kc =

For the Reaction PCl₅ (G)⇌ PCl₃ (G)+ Cl₂ (G),K_c =