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

Time required is 1.33 seconds

Step-by-step explanation:

For first order reaction, the rate law expression is:

`kt = ln ([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 =
`[(1)/(k)](ln[(0.830)/(0.260)])`

time =
`(1)/(0.870)(1.16) = 1.33 seconds`