Question

3. A reaction 2A 2B + C is known to follow second-order kinetics, with k = 7.20x10*M's' at 25.0 °C. (20 points) During one experiment, the initial concentration of A is [A]. = 0.120 M (a) Calculate the half-life (1,2), in hours, for this experiment. (b) Calculate the initial reaction rate (in M/s) for this reaction (4 points) (c) How long will it take (in hours) for the concentration of C to reach [C] = 0.0540 M (6 points) (d) If it is found that k = 1.80 x 10°M's at 35°C., calculate the activation energy, Ea (in kJ/mol) for this reaction. (6 points)

Answer 1

Given, rxn is following second onder kinetics So, we have k= III + L [A] CAJOJ Given, K= 7.20 x 10-4 M 's-1 [A] = 0.120M Half life in second onder rxn is, k(A). 720X10X0 120 =11574.0743 t = 3:21 hors Rate low rate = K[A]² = Initial rxn rate=7.20x10 4x (0.1200² - An n ot = 10036 X 16 5 M/S t=2 , [c] = 0.0540 = [A] = [A]o-2 [6] = 0.120- 2x0.0540 - 0.012 M 0.120 -0.012 ir 7 20x104 L 0.0120 120 - = 104166.66 S = 28.935 hours

When, T, = 25°c=298.15k, k, = 7.20 x 10 Mist When, T2= 35°C = 308.15k, k, = 1.80 x 103 mist As we know by Arrhenius eghi log kz - Ea [ + ] = log 1.80x10 3 = Ea x 308.15-298.15 7.20x10-4 19.14 298.15X308.15 Ea = 69811.894 J/mol = 69.811 kJ/mol =