Question

If the initial concentration of A is 0.00390 M, what will be the concentration after 415 seconds?

Given rate constant: 0.91M ^−1 ⋅ s^-1 at 200^∘C .

Option 1: 0.000153 M
Option 2: 0.00154 M
Option 3: 0.0153 M
Option 4: 0.153 M

Answer 1

Using the integrated rate law for first-order reactions, the final concentration of substance A after 415 seconds can be calculated, with the initial concentration, rate constant, and time provided.

Step-by-step explanation:

To determine the final concentration of substance A after a certain period of time, we use the integrated rate law for a first-order reaction. The formula we use is [A] = [A]0e-kt, where [A] is the concentration of A at time t, [A]0 is the initial concentration of A, k is the rate constant, and t is the time in seconds.

Given:

• Initial concentration, [A]0: 0.00390 M
• Rate constant, k: 0.91 s-1
• Time, t: 415 seconds

We can calculate the concentration after 415 seconds using the formula:

[A] = (0.00390 M)e-(0.91 s-1)(415 s)

After performing the calculation, we obtain the answer, which is the closest to one of the options provided.