A student studies the thermal decomposition of solid under identical temperature and…
CHEMISTRY · Single correct · A Level · Chemistry · Kinetics · Kinetics
Problem
A student studies the thermal decomposition of solid CaCO3 under identical temperature and pressure conditions in two separate trials.
• Trial 1: a single 5g marble chip is used.
• Trial 2: 5g of CaCO3 powder with average particle diameter one-tenth that of the marble chip is used.
Which statement best predicts the relative initial reaction rates for the two trials?
(a) Both trials have identical initial rates because each contains the same number of moles of CaCO3.
(b) Trial 1 is faster because the single large chip retains heat better, increasing the kinetic energy of its particles.
(c) Trial 2 is faster because its greater surface area increases the frequency of reactant–gas collisions.
(d) Trial 2 is slower because smaller particles provide less exposed surface area per particle, reducing the number of gas–solid collisions.