Question

A reaction has a rate constant of 0.00774 sec-1, how much of the compound (in mol/L) is left after 8.93 sec, if there was 0.652 mol/L at the start? (give answer to 3 decimal places)?

how do you know the order of the reaction???

Answer 1

0.608 mol/L compound is left after 8.93 sec

Step-by-step explanation:

This is a first order reaction because unit of rate constant is
`(time)^(-1)` (or
`sec^(-1)`)

For a first order reaction, integrated rate law is-

`ln(C_(0))/(C_(t))=k.t`

where
`C_(0)` is initial concentration of reactant,
`C_(t)` is concentration of reactant after t time and k is rate constant

Here
`C_(0)` = 0.652 mol/L, k = 0.00774
`sec^(-1)`) and t = 8.93 sec

So,
`ln((0.652mol/L)/(C_(t)))=0.00774 sec^(-1)* 8.93 sec`

So,
`C_(t)=0.608mol/L`