E1.2 Reaction Rate Constant

Example 1.2: A number of experiments were conducted to study the decomposition reaction of acetic anhydride (first order). Find the energy of activation and frequency factor if the following data apply:

Solution

· Plot ln(k) versus 1/T and draw a straight line.

Alternately, use method of least squares to obtain slope and intercept. The values of X, Y, XY, X², SY, SXY, SX² are presented.

· Slope, m (Equation 1.2):

· Energy of activation, E = -Rm = 1.9872 ´ (-1.736´10⁴) = 3.45 ´ 10⁴ cal/mol

· Intercept, I (Equation 1.3):

· Frequency factor, A = exp(I) = exp(27.631) = 1.0 ´ 10¹² s^-1.