Chemistry Rate Law?

Question

Consider the reaction aA-->Products.
[A]0 = 5.0 M and k = 1.0 × 10–2 (assume the units are appropriate for each case). Calculate [A] after 30.0 seconds have passed, assuming the reaction is: 

 

zero order

first order

second order

 

Answer 1

(a)

Step 1:

Initial concentration of A is .

Rate of constant  .

Find the  [A] at t = 30 sec in zero order .

Zero order Integrated rate law  : .

Where k = rate constant ,

              [A]₀ = initial concentration of A,

              t  is time.

Substitute , and sec .

Solution:

In zero order the concentration of reactant at sec  is .

Answer 2

(b)

Step 1:

Initial concentration of A is .

Rate of constant  .

Find the  [A] at t = 30 sec in first order .

First order Integrated rate law  : .

Where k = rate constant ,

              [A]₀ = initial concentration of A,

              t  is time.

Substitute , and sec .

Solution:

In first order the concentration of reactant at sec  is .

Answer 3

(c)

Step 1:

Initial concentration of A is .

Rate of constant  .

Find the  [A] at t = 30 sec in second order .

Second order Integrated rate law  : .

Where k = rate constant ,

              [A]₀ = initial concentration of A,

              t is time.

Substitute , and sec .

Solution:

In second order the concentration of reactant at sec is .