Question

The first-order decomposition of cyclopropane has a rate constant of 6.7 * 10-4 5-1. If the initial concentration of cyclopropane is 1.33 M, what is the concentration of cyclopropane after 644 s? OA) 0.43 M B) 0.15 M C) 0.94 M D) 0.86 M

Answer 1

D) 0.86 M

Step-by-step explanation:

Given that:

The rate constant, k = 6.7×10⁻⁴ s⁻¹

Initial concentration [A₀] = 1.33 M

Time = 644 s

Using integrated rate law for first order kinetics as:

`[A_t]=[A_0]e^(-kt)`

Where,

`[A_t]` is the concentration at time t

So,

`[A_t]=1.33* e^{-6.7* 10^(-4)* 644}`

`[A_t]=0.86 M`