The activation energy, Ea, for a particular reaction is 13.6 kJ/mol. If the rate constant at 475 K is 0.0450 1/min, then what is the value of the rate constant at 789 K? (R = 8.314 J/mol • K)

Answer 1

k = Ae^-Ea/RT

(e is a button on your calculator)

1. Solve for A at 475K
2. plug in variables
3. Ea= 13.6 Kj/mol
4. k = 0.045 s^-1
5. T = 475K
6. A= 1.408 s^-1
7. Since A and Ea are the same for a particular reaction, we use the value of A that we found with our new temperature
8. Plug in variables
9. E_a = 13.6 kJ/mol
10. T = 789 K
11. A = 1.408 s^-1
12. k = 0.1771 s^-1

Please let me know if you need further explanation or are still confused!

Please rate this 5 stars if helpful

Answer 2

Arrhenius equation:

ln (k2/k1) = -Ea/R (1/T2 - 1/T1)

k1 = 0.0450 min^-1

k2 = ?

Ea = 13.6 kJ/mol

R = 8.314 J/Kmol = 0.008314 kJ/Kmol (change units to agree with those of Ea)

T1 = 475K

T2 = 789K

Solve for k2:

ln (k2/0.0450) = -13.6 / 0.008314 (1/789 - 1/475)

ln (k2/0.0450) = -1636 (0.001267 - 0.002105)

ln (k2/0.0450) = 1.371

k2/0.0450 = 3.94

k2 = 0.177 min^-1 (3 sig. figs.)