Question

1.) (14 pts.) An extension of the Langmuir adsorption isotherm is when a catalyst has separate sites that selectively choose one material over another. An example of when this happens is the catalytic oxidation of H2S over a bed of iron oxide granules. The overall reaction is H2S + 12 02 → 2 S2 + H2O The proposed mechanism is provided on the following page where the reaction of the adsorbed O and H2S is the rate limiting step. H2S+S' H2S-S' O2 + 2S* H20-S* H2S-S' +0-S* → S-S' + H2O-S* 2S-S' → S2 + 2S' H2O-S* HH2O + S* (Constants: k1, k-1, K1) (Constants: k2, k-2, K2) (Rate constant: k3) (Rate constant: k4) (Constants: ks, k-s, K5) Determine the rate law for this reaction mechanism. (Hint: One of your bound concentrations will be problematic to find. Approximations are your friend.)

Answer 1

Considering as-s' kay S₂+28 the final step, the sale low for this reaction in destens . km [s=s'y? now, applying the steady state approximation, on lsos') , we get des -$'j at 2 = k, H, 3 - 5 3 Co-s*] - k , Cs-sº => [s-s'] = this. [Has- 'y co-sh] Now from the first & second step of the reaction, [H25-s'] = K, [H253 s] and co -5*J = key con le cas sos Es-s3. , mais elle sy toj con letto $or descartekups-siga 1 kg K, K 12 [H₂ s] [s'] coogle [A Scanned with CamScanner