A first-order reaction is 4.0 times faster at 50°C than it is at 25°C. What is the activation energy of this reaction?

Respuesta :

Answer:

[tex]Ea=44418.56\ J/mol[/tex]

Explanation:

Using the expression,

[tex]\ln \dfrac{k_{1}}{k_{2}} =-\dfrac{E_{a}}{R} \left (\dfrac{1}{T_1}-\dfrac{1}{T_2} \right )[/tex]

Where,

[tex]k_1\ is\ the\ rate\ constant\ at\ T_1[/tex]

[tex]k_2\ is\ the\ rate\ constant\ at\ T_2[/tex]

[tex]E_a[/tex] is the activation energy

R is Gas constant having value = 8.314 J / K mol  

[tex]k_2=4\times k_1[/tex]

[tex]T_1=25\ ^0C[/tex]  

[tex]T_2=50\ ^0C[/tex]  

The conversion of T( °C) to T(K) is shown below:

T(K) = T( °C) + 273.15  

So,  

[tex]T_1[/tex] = (25 + 273.15) K = 298.15 K  

[tex]T_2[/tex] = (50 + 273.15) K = 323.15 K  

So,  

[tex]\ln \dfrac{k_{1}}{4\times k_1} =-\dfrac{E_{a}}{8.314} \left (\dfrac{1}{298.15}-\dfrac{1}{323.15} \right )[/tex]

[tex]Ea=-\frac{\ln \frac{1}{4}\times \:8.314}{\left(\frac{1}{298.15}-\frac{1}{323.15}\right)}=44418.56\ J/mol[/tex]