A reaction has a rate constant of 0.0642 sec-1; how long will it take (in minutes) until 0.479 mol/L of the compound is left, if there was 0.502 mol/L at the start? (give answer to 3 decimal places)?

Respuesta :

Answer:

[tex]t=0.012\ min[/tex]

Explanation:

Using integrated rate law for first order kinetics as:

[tex][A_t]=[A_0]e^{-kt}[/tex]

Where,  

[tex][A_t][/tex] is the concentration at time t

[tex][A_0][/tex] is the initial concentration

Given that:

The rate constant, k = 0.0642 s⁻¹

Initial concentration [tex][A_0][/tex] = 0.502 mol/L

Final concentration [tex][A_t][/tex] = 0.479 mol/L

Time = ?

Applying in the above equation, we get that:-

[tex]0.479=0.502e^{-0.0642\times t}[/tex]

[tex]e^{-0.0642t}=\frac{0.479}{0.502}[/tex]

[tex]t=-\frac{\ln \left(\frac{0.479}{0.502}\right)}{0.0642}[/tex]

[tex]t=0.731\ sec[/tex]

Also, 1 sec = 1/60 min

So, [tex]t=0.012\ min[/tex]