E XERCISE 1 SOLUTION Lecturer: Miss Anis Atikah Ahmad Tel:

The reaction below is carried out isothermally in a continuous-flow reactor. A  B (a) Calculate both the CSTR and PFR reactor volume necessary to consume 99% of A (i.e., C A = 0.01 C A0 ) when the entering molar flow rate is 5 mol/h, assuming the reaction rate –r A is : (i) Zero order with reaction rate expression of –r A = k (k = 0.05 mol/h.dm 3 ) (ii) First order with reaction rate expression of –r A = kC A (k = s -1 ) (iii) Second order with reaction rate expression of –r A = kC A 2 ( k = 3 dm 3 /mol. h) The entering volumetric flow rate is 10 dm 3 /h. ( Note: F A = C A υ. For a constant volumetric flow rate υ=υ 0, then F A = C A υ 0. Also, C A0 =F A0 /υ 0 = [5 mol/h]/[10 dm 3 /hr]=0.5 mol/dm 3. ) (b) Calculate the time necessary to consume 99 % of species A in a 1000 dm 3 constant volume batch reactor with C A0 = 0.5 mol/dm 3 and r A in part a)(i),(ii), (iii). Q UESTIONS

(i) Substitute with the rate given

(i) Volume of PFR is same as volume for a CSTR since the rate is constant & independent of concentration.

(ii)

Substituting the values;

(iii)

(i) N A = C A V, C A = N A /V A Zero order:

(ii) (iii)

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