Question

N2O5 decomposes to form NO2 and O2 with first-order kinetics. The initial concentration of N2O5 is 3.0 M and the reaction runs for 3.5 minutes. If the rate constant, k, equals 5.89 × 10−3, what is the final concentration of N2O5?

Answer 1

Answer : The final concentration of
`N_2O_5` is, 2.9 M

Explanation :

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

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

where,

k = rate constant =
`5.89* 10^(-3)\text{ min}^(-1)`

t = time passed by the sample = 3.5 min

a = initial concentration of the reactant = 3.0 M

a - x = concentration left after decay process = ?

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

`3.5=(2.303)/(5.89* 10^(-3))\log(3.0)/(a-x)`

`a-x=2.9M`

Thus, the final concentration of
`N_2O_5` is, 2.9 M