Question

Manufacturing traditional clayware ceramics typically involves driving off the water of hydration in the clay minerals. The rate constant for the dehydration of kaolinite, a common clay mineral, is 1×10−4s−1 at 485 ∘c and 1×10−3s−1 at 525 ∘c. Calculate the activation energy for the dehydration of kaolinite.

Answer 1

The relation between activation energy, rate constant and temperature is given by Arrhenius equation

Arrhenius equation is

ln (K2/ K1) = Ea / R (1/T1- 1/T2)

K2 =  1×10−3s−1  T2 =  525 ∘C = 798 K

K1 = 1×10−4s−1  T1 =  485 ∘c = 758 K

Ea = ?

R = gas constant = 8.314 J / mol K

ln (K2/ K1) = ln (10^-3 / 10^-4) = 2.303 = Ea /8 .314 (1/758 - 1 / 798)

2.303 = Ea / 8.314 (0.00132 - 0.00125)

Ea = 2.303 X 8.314 / (0.00132 - 0.00125)  = 273530.6 J / mole

Ea = activation energy = 273.531 kJ / mole