in a certain solvent is first order with respect to (CH3) 3CBr and zero order with respect to OH2. In several experiments the rate constant k was determined at different temperatures. A plot of ln (k) versus 1/T was constructed that resulted in a straight line with a slope of 21.10 3 104 K and a y intercept of 33.5. Assume that k has units of s21. a. Determine the activation energy for this reaction. b. Determine the value of the frequency factor A. c. Calculate the value of k at 258C.

Question

Chemistry

Mateo Burke

14 March, 11:26

in a certain solvent is first order with respect to (CH3) 3CBr and zero order with respect to OH2. In several experiments the rate constant k was determined at different temperatures. A plot of ln (k) versus 1/T was constructed that resulted in a straight line with a slope of 21.10 3 104 K and a y intercept of 33.5. Assume that k has units of s21. a. Determine the activation energy for this reaction. b. Determine the value of the frequency factor A. c. Calculate the value of k at 258C.

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Answers (1)

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Potts · Answer 1

Ea = - 175.45J

A = 3.5*10^14

k=3.64 * 10^14 s^2.

Explanation:

From

ln k = - (Ea/R) (1/T) + ln A

This is similar to the equation of a straight line:

y = mx + c

Where m = - (Ea/R)

c = ln A

y = ln k

a)

Therefore

21.10 3 104 = - (Ea/8.314)

Ea = - (21.10 3 104*8.314)

Ea = - 175.45J

b) ln A = 33.5

A = e^33.5

A = 3.5*10^14

c)

k = Ae^-Ea/RT

k = 3.5*10^14 * e^ - (-175.45/8.314*531)

k = 3.64 * 10^14 s^2.