Given:
The amount at 120 secs and 200 secs is respectively,
[tex]\begin{gathered} A(120)=0.06 \\ A(200)=0.04 \end{gathered}[/tex]
To find: The average rate of the reaction from 120 to 200 seconds.
Explanation:
Using the average rate of change formula,
[tex]Average\text{ rate =}\frac{f(b)-f(a)}{b-a}[/tex]
Here, a = 120 and b = 200.
Substituting the above values we get,
[tex]\begin{gathered} Average\text{ rate}=\frac{A(200)-A(120)}{200-120} \\ =\frac{0.04-0.06}{200-120} \\ =\frac{-0.02}{80} \\ =-0.00025 \end{gathered}[/tex]
Final answer:
The average rate of the reaction is -0.00025mol/L/sec.
