Question

The rate constant for this second-order reaction is 0.460 M–1·s–1 at 300 °C. A--->Products. How long (in seconds) would it take for the concentration of A to decrease from 0.850 M to 0.360 M?

Answer 1

Given data for given second order reaction is,

Rate constant k₂ = 0.460 M^-1s^-1 .

Initial concentration[A₀] = 0.850 M

Final concentration [A_t] = 0.360 M.......after time t seconds

t = ? sec.

For second order reaction we have the rate expression as,

( 1/[At] - 1/[A₀] ) = k₂t

let us put all known things

so, (1/0.360 - 1/0.850 ) = 0.460 x t

2.778 - 1.176 = 0.460 x t

1.602 = 0.460 x t

so, t = 1.602 / 0.460

t = 3.48 seconds

It would take 3.48 s for decrease of concentration from 0.850 M to 0.360 M.