Question

Dinitrogen pentoxide, N2O5, decomposes by first-order kinetics with a rate constant of 0.15 s-1 at 353 K.

(a) What is the half-life (in seconds) for the decomposition of N2O5 at 353 K?

(b) If [N2O5]0 = 0.0579 mol·L-1, what will be the concentration of N2O5 after 4.0 s?

(c) How much time (in minutes) will elapse before the N2O5 concentration decreases from 0.0579 mol·L-1 to 0.0143 mol·L-1?

Answer 1

a. k = 0.693/t_1/2
b. ln(No/N) = kt.
No = given
N =?
k = from part a.
t = 4 s.

c.
same equation as b but
No = given
N = given
k = from a
t = ?
Note that part a is given in seconds, part c wants the answer in min.