Question

The rate constant for the first-order reaction below is 0.0385 M/s.A - B3rd attempthd See Periodic Table SIf the reaction is begun with an initial concentration of A equal to 0.95 M, what is the concentration of A after 34.01 s?M

Answer 1

Kinetics - Rate of a reaction - Reaction order

A first order reaction is a reaction in which the rate is proportional to the concentration of only one reactant.

Answer:

We have the following reaction and reaction rate:

`\begin{gathered} A\rightarrow B \\ \\ rate:\text{ 0.0385}(M)/(s) \end{gathered}`

The rate of the reaction is expresed as:

`rate=-(\lbrack A_(final)\rbrack-\lbrack A_(initial)\rbrack)/(\Delta t)`

In this case:

`\begin{gathered} \lbrack A_(initial)\rbrack=0.95M \\ \Delta t=34.01s \end{gathered}`

So now we calculate the final concentration of A:

`\begin{gathered} \lbrack A_(final)\rbrack=\lbrack A_(initial)\rbrack-rate*\Delta t \\ \\ \lbrack A_(final)\rbrack=0.95M-0.0385(M)/(s)*34.01s \\ \\ \lbrack A_(final)\rbrack=0.3594M \end{gathered}`

So the final concentration of A is 0.3594M.