Question

The rate constant for this first‑order reaction is0.870 s−1 at 400 ∘C. A⟶products How long, in seconds, would it take for the concentration of A to decrease from 0.830 M to 0.260 M?

Answer 1

Answer:

Time required is 1.33 seconds

Explanation:

For first order reaction, the rate law expression is:

$kt = ln \frac{[A_{0}]}{[A_{t}]}$

Where

A0 = initial concentration = 0.830 M

At = concentration after time t = 0.260 M

t = time in seconds = ?

k = rate constant = 0.870 s⁻¹

time = $[\frac{1}{k}](ln[\frac{0.830}{0.260}])$

time = $\frac{1}{0.870}(1.16) = 1.33 seconds$