Activation energy for the reaction is 33.1 kJ/mol. Strategy: A modified form of the Arrhenius equation relates two rate constants at two different temperatures [see Equation 14.13]. Make sure the units of R and E are consistent. Solution: The data are k = 4.68x10^-2 s^-1, K = T = 298 K, T' = 375 K. Substituting in Equation 14.13: 8.314 J/Kmol * (1/298 K - 1/375 K). We convert E to units of J/mol to match the units of R. Solving the equation gives: ln(4.68x10^-2) = -2.74 - 4.68x10^2 * (1/298 K - 1/375 K). A = 0.7241. Check: The rate constant is expected to be greater at a higher temperature. Therefore, the answer is reasonable. Practice Exercise: The first-order rate constant for the reaction of methyl chloride (CHCl) with water to produce the activation energy is 116 kJ/mol.