Question

The rate constant for this first‑order reaction is 0.470 s − 1 0.470 s−1 at 400 ∘ C. 400 ∘C. A ⟶ products A⟶products How long, in seconds, would it take for the concentration of A A to decrease from 0.920 M 0.920 M to 0.380 M?

Answer 1

Answer : The time taken by the reaction is, 1.88 s

Explanation :

Expression for rate law for first order kinetics is given by:

`t=(2.303)/(k)\log(a)/(a-x)`

where,

k = rate constant =
`0.470s^(-1)`

t = time passed by the sample = ?

a = initial amount of the reactant = 0.920 M

a - x = amount left after process = 0.380 M

Now put all the given values in above equation, we get

`t=(2.303)/(0.470)\log(0.920)/(0.380)`

`t=1.88s`

Therefore, the time taken by the reaction is, 1.88 s