A student observes that the tangent to a reactant’s concentration–versus–time curve…
CHEMISTRY · Single correct · CBSE · Chemistry · Chemical Kinetics · Chemical Kinetics
Problem
A student observes that the tangent to a reactant’s concentration–versus–time curve at t=120s is noticeably less steep than the tangent at t=20s. Which statement most strongly accounts for this observation?
(a) Temperature gradually decreases during the run, so molecular speed and collision frequency are lower at 120s
(b) Catalyst particles become consumed over the course of the reaction, so catalytic activity is essentially lost by 120s
(c) Reactant concentration is lower at 120s, so fewer effective collisions occur each second
(d) As product builds up, the reverse reaction increasingly competes with the forward reaction, reducing the net rate at 120s