A generic reversible reaction
A(g) ⇌ B(g)
occurs in a 1.5 L rigid container at constant temperature. Two particulate snapshots of the same system are taken:
Snapshot I (time t₁): 9 A molecules, 3 B molecules
Snapshot II (time t₂): 6 A molecules, 6 B molecules
The equilibrium constant for the reaction at this temperature is Kc = 1.2.
(a) Calculate Qc at time t₁ using Snapshot I and determine whether the system is at equilibrium at that time.
(b) Calculate Qc at time t₂ using Snapshot II and determine whether the system is at equilibrium at that time.
(c) Predict whether the number of A molecules present at a future time t₃ (long after t₂) will be greater than, less than, or equal to the number present in Snapshot II. Support your prediction with quantitative or qualitative reasoning based on your answers to parts (a) and (b).
(d) Sketch a qualitative concentration-versus-time graph showing [A] and [B] from t₁ through the time the system finally reaches equilibrium. Clearly label the relative positions of t₁, t₂, and the point where equilibrium is first achieved.