t Applying the Collision Model In the collision model it is assumed that reactio
ID: 1008833 • Letter: T
Question
t Applying the Collision Model In the collision model it is assumed that reactions occur as a result of collisions between molecules with the correct kinetic energy and orientation. The minimum energy required for a reaction to occur when molecules collide is called the activation energy, Ba. The number of collisions that are favorably oriented for a reaction is described by the frequency factor, A. The Arrhenius equation relates both of these factors to the rate constant, k Ea/(R-T) where R 8.314 J/(mol K) and T is the temperature in kelvins previous l 12 of 43 mat must be overcome TO reactromto occur. Une mequeri fraction of collisions that are favorably oriented; it can be thought of as the likelihood that a reaction will occur. Fraction of molecules The exponential term in the Arrhenius equation is equal to the fraction of molecules f, with kinetic energy greater than or equal to the activation energy: e-Ea/(R-T) Most scientific calculators have an ex function as the second function of the LN button. Part B Certain reaction with an activation energy of 175 kJ/mol was run at 495 K and again at 515 K What is the ratio of f at the higher temperature to f at the lower temperature? Express your answer numerically using one significant figure. 515 7495 Submit Hints My Answers Give Up Review Part Incorrect, Try Again Continu Provide FeedbackExplanation / Answer
logf515/f495 = Ea/2.303R [1/T1 -1/T2]
Ea = 175kj/mole = 175000j/mole
T1 = 495K
T2 = 515K
R = 8.314j/mole-k
logf515/f495 = Ea/2.303R [1/T1 -1/T2]
logf515/f495 = 175000/2.303*8.314 [1/495 -1/515]
= 9139.74 [0.002020-0.001941]
= 9139.74*0.000079
logf515/f495 = 0.722
f515/f495 = 10^0.722 = 5.272
f515/f495 = 5.272/1
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