# The initial concentration of Compound A is 1.5 mol/L. It disappears in a zero-order reaction with a rate constant of #"0.2 mol·L"^"-1""s"^"-1"#. What is its concentration after 15 s?

##### 1 Answer

Apr 2, 2014

You use the integrated rate law for a zero order reaction:

[A] = [A]₀ - *kt*.

Insert the values of [A]₀, *k* and *t* into the equation and solve for [A].

You will get a value of -

It is impossible to have a negative concentration. This tells you that all the A has disappeared before 15 s.

If you set [A] = 0 and solve fot *t*, you get

All the A has vanished after 8 s, so there is none after 15 s.