28 January
For a First-order reaction A → B
Rate Law: Rate = k[A]
Integrated Rate Law: ln [A]t = -kt + ln [A]0
Plot of ln [A]t vs. Time results in a linear graph
For a Second-order reaction A → B
Rate Law: Rate = k [A]2
Integrated Rate Law: 1/[A]t = kt + 1/[A]0
Plot of 1/[A]t vs. Time results in a linear graph
2N2O5 (g) → 4NO2 (g) + O2 (g)
The rate constant, k, for this reaction is 0.00681 s-1
What is [N2O5] at 1.0 hour if [N2O5]0 = 0.200 M?
Rate = k [N2O5]
Ln [N2O5]360 = -(0.00681)(360) + ln[.2]
Ln [N2O5]360 = -26.125
[N2O5]360 = 4.5 x 10-12 M
Answers that wouldn’t make sense here are greater than 2.0 or negative (since it’s a reactant rate, it’s
decreasing)
What fraction has decomposed by 30 seconds?
Ln [N2O5]30 = -(0.00681)(30) + ln [N2O5]0
Ln [N2O5]30 – ln [N2O5]0 = -(0.00681)(30)
