Chemical Kinetics

 

 32) 6.82 x 10-3 s-1          n = 0.0250 mol N2O5          V = 2.0 L

       N2O5(g) 2NO2(g) + O2(g)

 

       (a) Δt = 2.5 min x 60 s/min = 150 s

 

             ln[A]t = -kt + ln[A]0

             ln[N2O5]t = -kt + ln[N2O5]0 = -kt + ln[n/V]0

             ln[N2O5]t = -6.82 x 10-3 s-1 x 150 s + ln[0.0250/2.0]0

             ln[N2O5]t = -5.41

             [N2O5]t = e-5.41 = 4.5 x 10-3 M

             [N2O5] = n/V

             nN2O5 = 4.5 x 10-3 mol N2O/L x 2.0 L = 9.0 x 10-3 mol N2O5

             

       (b) nN2O5 = 0.010 mol N2O5

 

             [N2O5]t = n/V = 0.010 mol N2O5/2.0 L = 0.0050 M

             ln[N2O5]t = -kt + ln[N2O5]0

             ln(0.0050) = -6.82 x 10-3 s-1 x Δt + ln(0.0125)

              ln(0.0050/0.0125) = -6.82 x 10-3 s-1 x Δt

             Δt = 130 s

             

       (c) [N2O5]0 = n/V = 0.0250 mol N2O5/2.0 L = 0.0125 M

            [N2O5]t1/2 = 1/2[N2O5]0

            ln[N2O5]t = -kt + ln[N2O5]0

            ln(1/2 x [N2O5]0/[N2O5]0) = -6.82 x 10-3 s-1 x Δt

            Δt = 102 s