Question

The mechanism of the pyrolysis of acetaldehyde corresponding to the chemical reaction CH3CHO(8) CH4(8) +CO(g) at 520 °C and 0.2 bar is kị kg CHCH0g) CH3 g) + CH0g) CH3(g) + CH3CHO(g) = CH4(g) + CH3COg) CH3CO(g) = CO(g) + CH3(g) CH3(g) + CH3(g) = C2H6() Is this reaction a chain reaction? If so, identify the initiation, propagation, inhibition, and termination step(s). Using the steady state approximation for intermediate species CH3(g) and CH3CO(g), derive the rate law 1/2 kz [CH2CHO]3/2

Answer 1

Question is solved using basic concepts of steady state approximation for transient species.

solution - The mechanism of bysalysis of acetaldehyde is as given - CH₃ CHOG) - CH₂ CG) + CHO (8) ki (13(g) + CM₂ CHOCO) CM₂ (8) + M3C0 (g) kz CH3cOcg) - COCA) + CH3 (8) kg CH₂ + CH3 C2H6(9) kq Yes, it is a chain reaction The initiation step- I where the chain carrier foolm CH3CHOCH) → (438) + CHOCB) is uitation steps. Preopagation step- The steps where chain carrier produced in the initiation step attack other reactant molecule CH3 (8) + CH3 CHO Cha (g) + cm3 CO 2 Cuzcoch) — Coco + C4,C8) in prepagatiew both comes Termination step- a step ahore carrier combine and end the chain Cu₂+ CH₂ GMC (8) is termination step. Inhibition step e a step wtou covjers are removed by a process other than termination. Here we can say step 18 inhibition steps which. is kind of propagation step. POLO

1 DATE: PAGE NO.: Abby ing_xleedy_state approximation for CH3CB) — unde Jaumation of chy-z_ rate of dicereposition of chy _d [cm3]. z-03 Kj (CHECHO] - Kz [cus) (CHECMO] dt - + kz [06C0] =zka (CH3) O Affilging steady state approximation for Cuzco rate of formation of Azco z sale of decomposition of Choco d chec) =0 = [kg][c c] - k, chọco] - dt adding equeflon and we get k. [CH3CHO) – Ke [cus.] [como] tkz [onO] – Ka [eng]' + ky [erg/ [enemi — ks[chy [0] zó ky Tony CHO] -2kq. [cmg]' zones ka rongy? z Ry Cong CHO] [ch] z ki [CH₂ CMO] & 2 kq [CH]z La Concord)_- 3 12144 Now we can write rate for cha as d [Cha] dt

DATE: PAGE NO.: d[Chor] z kz [eng] [cm3 CHO] dt putting the value of [chs from equation & we get decine) e la mia congruo x [Ctecto] d[ematent e sa conso ľ poneroz' d [cho] dt KL192 kg (Cng CHO] (269