At 460 K, the rate constant for this reaction is k = 5.8 × 10–6 s–1 and the activation energy is Ea = 265 kJ/mol. What is the frequency factor for this reaction?

Question

The compound 1,1-difluoroethane decomposes at elevated temperatures to give fluoroethylene and hydrogen fluoride according to the equation: CH3CHF2----->CH2CHF+HF

Answer 1

You want to use the following formula, also called the Arrhenius equation, which describes the effect of temperature or a catalyst on the rate constant of the reaction:

k = Ae^-Ea/(RT)

where

k - rate constant

A - frequency factor

Ea - activation energy of equation

T- temperature of reaction (K)

R - ideal gas constant (8.314J/K⋅mol)

The question provides you with k, Ea, and T. Plug these values into the formula and solve for A. Hint - make sure you convert units of Ea into J.

Happy to walk through the answer step by step - please feel free to book some time with me on instant book!

Answer 2

The Arrhenius equation is

k = Ae^-Ea/(RT)

Taking ln of both sides, we get

ln k = lnA - (Ea/RT)

Plugging in the given values (and converting R to 0.008314 kJ/Kmole) we have

ln 5.8x10^-6 = ln A - (265/0.008314 * 460)

-12.06 = ln A - 69.29

ln A = 57.23

A = 7.16x10²⁴ M^-1s^-1