HI (g) + CH3I (g) - > CH4 (g) + I2 (g) the rate constant is 0.28 L/Mol*s at 300*C and 0.0039 L/Mol*s at 227*C. a) What is the Activation energy of this reaction. b) What is k at 400*C

(a) The activation energy (Ea) is 3284.6 L. atm/mol

(b) At 400°C, k is 0.6579 L/Mol*s

Explanation:

(a) The activation energy for the reaction is determined using Arrhenius equation

In (k2/k1) = - Ea/2.303R [1/T2 - 1/T1]

k2 = 0.28 L/mol*s, k1 = 0.0039 L/mol*s, R = 0.082057 L. atm/molK, T2 = 300°C = 300+273K = 573K, T1 = 227°C = 227+273K = 500K

In (0.28/0.0039) = - Ea/2.303*0.082057 [1/573 - 1/500]

4.27 = - Ea (-0.0013)

4.27 = 0.0013Ea

Ea = 4.27/0.0013 = 3284.6 L. atm/mol

(b) The value of k at 400°C is determined by interpolation

T (°C). Rate constant (L/mol*s)

227. 0.0039

300 0.28

400 k

400-227/300-227 = k-0.0039/0.28-0.0039

2.37 = k-0.0039/0.2761

k-0.0039 = 2.37*0.2761

k-0.0039 = 0.654

k = 0.654+0.0039 = 0.6579L/mol*s