Molecular collision energies—refer to Figure 3-4 and to the Wolfram and Python LEP 3-1. cdf Variation of Energy Distribution with
Temperature.
1. What fraction of molecular collisions have energies less than or equal to 2.5 kcal at 300 K? At 500 K?
2. What fraction of molecular collisions have energies between 3 and 4 kcal/mol at T = 300 K? At T = 500 K?
3. What fraction of molecular collisions have energies greater than the activation energy E_A = 25 kcal at T = 300 K? At T = 500 K?

Figure 3-4

Transcribed Image Text:

f(E,T)dE=2(1KBT)3/2E1/2exp[-EkBT]dE(3-21) 0.9 m 0.81. 0.8 0.7 0.6 0.5 RET) 0.4 kcal 0.3 0.2 0.1 0 T - 300 K 0 0.25 0.35 The fraction of collisions with energies between 0.25 and 0.35 kcal/mol is approximately f(ET)dE= (0.81 kcal/mol)-1 x (0.1 kcal/mol) = 0.081; that is, 8.1% of the molecular collisions have energies between 0.25 and 0.35 kcal/mol. T> T T = 500 K I 1.5 I 2 2.5 3 E kcal mol 3.5 The fraction of collisions at 7 500 K that have energy EA of 2.5 kcal/mol or greater 4 4.5 6