Question

This reaction:

A--->B+C

is known to be second order with respect to A and to have a rate constant of 0.243M^-1s^-1 at 297K. An experiment was run at this temperature where [A]_o=0.391M. Calculate the concentration of B after 0.161s have elapsed.

Answer 1

given a second order reaction

we know that

for a second order reaction

1 / [A] = 1/[Ao] + kt

given

rate constant (k) = 0.243

time (t) = 0.161

also given

[Ao] = 0.391

using these values

we get

1 / [A] = 1/[Ao] + kt

1 / [A] = 1/ 0.391 + ( 0.243 x 0.161 )

1/[A] = 2.5966

[A] = 0.3851

so

the concentration of A after 0.161 s is 0.3851

so

[A] reacted = initial - final

[A] reacted = 0.391 - 0.3851

[A] reacted = 5.9 x 10-3

from the reaction

we can see that

[B] formed = [A] reacted = 5.9 x 10-3

so

the conc of B after 0.161 s is 5.9 x 10-3 M