Let the reaction be A⟶k Product Rate =k[ A]1.5×10−2 molL −1min−1=k[0.5]k=0.51.5×10−2=3×10−2 min−1t1/2=k0.693⇒t1/2=3×10−20.693=0.231×102 min⇒t1/2=23.1 min Related Theory Decay profiles for first-order reactions with large and small rate constants 