Question

The conversion of cyclopropane an anesthetic, to propylene has a rate constant k=1.3 *10^-6 s^-1 at 400 Celcius and k=1.1 *10^-5 s^-1 at 430 Celcius. What is the activation energy?What is the value of the frequency factor A for this reaction? What is the rate constant for this reacton at 350 C?

Answer 1

Apply:

K1 = 1.3*10^-6; T1 = 400°C = 673 K

K2 = 1.1*10^-5; T2 = 430°C = 703 K

Ea...

ln(K2/K1) = E/R*(1/T1-1/T2)

E = ln(K2/K1)*R / (1/T1-1/T2)

E = ln((1.1*10^-5)/(1.3*10^-6)) / 8.314 / ( 1/(673 ) - 1/703 )

E = 4050.83 J/mol

find A:

K = A*exp(-E/RT))

1.3*10^-6 = A*exp(-4050.83/(8.314*673))

A = (1.3*10^-6) / (exp(-4050.83/(8.314*673))) = 26813*10^-6

rate constant at T = 350|C = 623

ln(K2/K1) = E/R*(1/T1-1/T2)

ln(K2/(1.1*10^-5) = 4050.83/8.314 * (1/703) - 1/(623))

K2 = (1.1*10^-5)*exp(4050.83/8.314 * (1/703) - 1/(623))) = 2.19630*10^-5 s^-1