A reaction mechanism for the thermal decomposition of compound X is proposed: Step 1:…
CHEMISTRY · Single correct · AP · Chemistry · Kinetics · Kinetics
Problem
A reaction mechanism for the thermal decomposition of compound X is proposed:
Step 1: X Y (fast, reversible)
Step 2: Y Z (slow, irreversible)
The vessel is closed, and the temperature is held constant. After a long time, which statement best describes the composition of the system?
(a) Species Y accumulates because it is produced quickly in Step 1 but consumed slowly in Step 2, so most of the mixture is Y.
(b) Only species Z is present because the irreversibility of Step 2 forces Step 1 to stop entirely.
(c) Species Z predominates, but appreciable amounts of X remain because the reversibility of Step 1 continually shifts the equilibrium to the left.
(d) All three species are present in dynamic equilibrium because the closed system at constant temperature must reach an overall equilibrium.