Kinetics Past boards

Question 1

elementary liquid-phase reaction 𝐴 + 2𝐵 ⇄ 𝑅 with rate equation −𝑟𝐴 = −
1
2
𝑟𝐵 = (12.5 L
2
/mol2
∙ min)𝐶𝐴𝐶𝐵
2 − (1.5 min−1
)𝐶𝑅 is to
take place in a 6-L steady-state mixed-flow reactor. Two feed streams, one containing 2.8 mol A/liter and the other containing 1.6 mol
B/liter, are to be introduced at equal volumetric flowrates into the reactor, and 75% conversion of the limiting component is desired.
Assume a constant density throughout. Calculate the following:
1. Concentration of B when mixed with A
2. Final concentration of B
3. Flowrate of each stream

Answer 1

Answer: 0.8 M
Answer: 0.2 M
Answer: 1 L/min

Question 2

You are asked to recommend, with reasons, the most suitable type of equipment for carrying out a gas-liquid reaction
between a gas A and a solution of a reactant B. Particulars of the system are as follows:
Concentration of B in solution = 5 kmol/m3
Diffusivity of A in the solution = 1.5 × 10–9 m2
/s
Rate constant of the reaction (A + B → products; second order overall) = 0.03 m3
/kmol·s
For bubble dispersions (plate columns, bubble columns, agitated vessels) take kL as having a range from 2 × 10–4
to 4 × 10–4 m/s. For
a packed column, take kL as having a range from 0.5 × 10–4
to 1.0 × 10–4 m/s. Calculate the following:
1. the value of √𝑘2𝐶𝐵𝐿𝐷𝐴
2. the range of β for bubble dispersion and packed column
3. the suitable equipment for the reaction

Answer 2

Answer: 1.5 × 10–5 m/s
Answer: β = 0.0375 to 0.075 (bubble dispersion), β = 0.15 to 0.3 (packed
column)
Answer: bubble dispersion (agitated vessel)