11.3. Zero-order. First-order. Second-order reaction Be able to write rate laws for Zero-order and First-order reactions Half-life(tin): Att=tin, C=0.5 C For the first-order reaction, ti/ is independent of initial concentration (In 2)/k Units of rate constant k for d ifferent order of reactions (a). Ele (b). Change ofk with T: In(k2/k1)=-Ea/[R(1/T2-1/Tu)I (c). If there is one slowest step, this step is the rate determining step (d ). If there is no slowest step, use" Steady-state approximation "of any intermediates Summary and Exercise Class #4 Final exam11.3．Zero-order, First-order, Second-order reaction  Be able to write rate laws for Zero-order, and First-order reactions  Half-life (t1/2): At t = t1/2, C = 0.5 C0  For the first-order reaction, t1/2 is independent of initial concentration: t1/2 = (ln 2) / k  Units of rate constant k for different order of reactions 11.4．Reaction mechanism (a)．Elementary reactions (b)．Change of k with T: ln (k2/k1) = – Ea / [R (1/T2 – 1/T1)] (c)．If there is one slowest step, this step is the rate determining step. (d)．If there is no slowest step, use “Steady-state approximation” of any intermediates Summary and Exercise Class #4 1 class Final Exam