The rate constant k for a first-order reaction ... - SS2 Chemistry Chemical Kinetics Question

For a first-order reaction, the rate equation is given by:

rate = k[A]

We can rearrange the equation to solve for the concentration:

rate = k[A]

[A] = rate / k

Given that the rate constant (k) is 0.025 s^-1 and the initial concentration ([A]₀) is 0.10 M, we can substitute these values into the equation:

[A] = (rate / k) = ([A]₀) x e^(-kt)

[A] = (0.10 M) x e(-0.025 s^-1 x 40 s)

[A] ≈ 0.033 M

Therefore, the concentration of the reactant after 40 seconds is approximately 0.033 M.