A reaction taking place in the Earth's upper atmosphere is:?

Question

O3 + NO O2 + NO2

This is a second order reaction with a rate constant of

2.09 x 107 L/mol/s at 100oC. The activation energy of this

reaction is 10.3 kJ/mol. What is the rate constant at -80oC?

Answer 1

Use this form of the Arrhenius equation:

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

Just substitute:

ln(2.09x10^7/k2) = [(10,300 J/mol)/(8.314 J/L*mol)] [(1/193 K)-(1/373 K)];

Solving, k2 = 9.47x10^5 L/mol/s.

Another way to do it is to substitute into k = A e^(-Ea/RT) for the 100 °C case, solve for A, then resubstitute the -80 °C data, including A, to solve for the 2nd k.