Question

N2O5 decomposes to form NO2 and O2 with first-order kinetics. How long does it take for the N2O5 concentration to decrease from its initial value of 2.75 M to its final value of 1.85 M, if the rate constant, k, equals 5.89 × 10−3?

Answer 1

67.3 s

Step-by-step explanation:

The equation for the reaction can be represented as:

N₂O₅ ⇄ NO₂ + O₂

Rate (k) =
`5.89 * 10^{-3`

Rate law for first order is expressed as:

In [A] = -kt + In [A]₀

Given that:

[A] = Final Concentration = 1.85 M

[A]₀ = Initial Concentration = 2.75 M

time-taken = ???

substituting our given data; we have:

In[1.85] = -[5.89 × 10⁻³](t) + In [2.75]

t =
`(In(2.75)-In(1.85))/((5.89*10^(-3))`

t =
`(0.3964)/(5.89*10^(-3))`

t = 67.3 s