Consider: Cl 2 (g) + PCl (g) ↔ PCl 5 (g)

Initial [ ]’s of Cl 2 and PCl 3 are shown in the following data table and the concentration changes

are recorded at various time periods after the reaction progresses towards equilibrium.

Reaction time (sec) [Cl 2 ] mol/L [PCl 3 ] mol/L [PCl 5 ] mol/L

0 1.00 1.00 0.00

20 0.90 0.90 0.10

40 0.80 0.80 0.20

60 0.75 0.75 0.25

80 0.71 0.71 0.29

100 0.71 0.71 0.29

120 0.71 0.71 0.29

From observing this data table:

C. At 40 seconds which reaction is faster, forward or reverse? ____________________