Discussion
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- Question
At 25°C, the saturation concentration of oxygen in water is 1.26 mmol/l and the partial pressure of oxygen is 1 atm. The Henry's law constant will be
Options- A. 0.793atml/mmol
- B. 0.207atml/mmol
- C. 1.26 atml/mmol
- D. 8.74 atml/mmol
- Correct Answer
- 0.793atml/mmol
- 1. Which of the following will have the highest surface area available for oxygen transfer?
Options- A. A shake flask
- B. A standing test tube
- C. A non-sparged stirred tank reactor agitated at 400 rpm
- D. A sparged stirred tank reactor agitated at 400 rpm Discuss
- 2. Which of the following is most likely to cause an increase in the rate of oxygen transfer into a particular aerated fermentation system?
Options- A. Addition of antifoams
- B. Increase in temperature
- C. Increase in stirrer speed
- D. Both (a) and (b) Discuss
- 3. Which of the following type(s) of stirrer can be used for microbiological processes?
Options- A. Mig
- B. Intermig
- C. Turbine
- D. All of these Discuss
- 4. Which of the following would be best described as an axial flow impeller?
Options- A. An impeller with blades pitched at 45° to the vertical
- B. An impeller which directs liquid flow towards the base of the reactor
- C. Both (a) and (b)
- D. An impeller with blades pitched at 75° to the vertical Discuss
- 5. Surface renewal theory predicts that the mass transfer coefficient is
Options- A. directly proportional to the square root of the molecular diffusivity
- B. inversely proportional to the square root of the molecular diffusivity
- C. directly proportional to the cube root of the molecular diffusivity
- D. indirectly proportional to the cube root of the molecular diffusivity Discuss
- 6. The oxygen transfer rate in a bioreactor will increase if
Options- A. oil is added
- B. antifoam is added
- C. detergent like molecules are added
- D. increase in the reactor temperature Discuss
- 7. Power number is expressed as
Options- A. P0 / N2Di3?
- B. P0 / N3Di5?
- C. P0 / N3Di3?
- D. P0 / N2Di2? Discuss
- 8. Which of the following impellers will provide radial flow?
Options- A. Paddles
- B. Flat blade turbines
- C. Disk flat blade turbines
- D. All of the above Discuss
- 9. The average concentration of oxygen in the boundary layers surrounding the bubbles (Co*) in a reactor is normally determined by
Options- A. ultra-small dissolved oxygen probes
- B. laser based photographic systems
- C. measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor
- D. measuring the steady state concentration of oxygen in the bulk liquid after inoculation of the reactor Discuss
- 10. Which of the following best explains the reasons for using axial flow impellers in crystallization and precipitation reactions?
Options- A. Crystal and precipitates are not too small, so as to ensure easy separation of the solids from the mother liquor
- B. Crystals and precipitates are thoroughly broken down, so as to ensure easy separation of the solids from the mother liquor
- C. Both (a) and (b)
- D. Axial flow impellers provide low shear, energy efficient mixing conditions Discuss
Agitation and Aeration problems
Search Results
Correct Answer: A sparged stirred tank reactor agitated at 400 rpm
Correct Answer: Increase in stirrer speed
Correct Answer: All of these
Correct Answer: Both (a) and (b)
Correct Answer: directly proportional to the square root of the molecular diffusivity
Correct Answer: detergent like molecules are added
Correct Answer: P0 / N3Di5?
Correct Answer: All of the above
Correct Answer: measuring the steady state concentration of oxygen in the bulk liquid prior to inoculation of the reactor
Correct Answer: Crystal and precipitates are not too small, so as to ensure easy separation of the solids from the mother liquor
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