EHS 429 MAIN EXAMINATION PAPER 2018 DECEMBER QUESTION TWO (5 Marks each) 2A. Consider the following sets of parallel reactions taking place in the same reactor: A B2C A+B D Reaction (i) Reaction (ii) Kinetics study showed that reaction (i) proceeds at the rate of 0.1 moles per hour (reduction for A and B). On the other hand reaction (ii) proceeds at the rate of 0.2 moles per hour (reduction for A and B and production for D. i. State the overall rate of reaction of the system as a whole. ii. iii. Assuming the reaction rates stay constant how many moles of C and D are produced after 6 hours of reaction? Assuming the reaction rates stay constant how many moles of A and B are removed after 6 hours of reaction? 2B. List the six sequential steps that occur in a typical heterogeneous chemical reaction. 2C. Plot a profile of tracer salt concentration versus time for i) plug low reactor and ii) completely mixed flow reactor assuming that a tracer of known mass is added to the inlet of the reactor and the tracer salt concentration at the outlet flow is being measured with time after addition of the tracer salt. Initially the reactor flow has negligible concentration of the tracer salt. Assume that the retention time of the reactor is T Volume/flow rate. = 2D. An ion exchange resin that weighs 200 kg is employed for the removal of calcium from a given hard water, the concentration of calcium in the raw water to be treated is 400 mg/L. The ion exchange resin treats the water so that the treated water contains only 20 mg/L of Calcium. If a total of 60,000 liters water were treated, what will be the ion exchange resin capacity? 2E. State the advantages and disadvantages of choosing ion exchange media that has greater affinity for the ions to be exchanged. Page 4 of 8
EHS 429 MAIN EXAMINATION PAPER 2018 DECEMBER QUESTION TWO (5 Marks each) 2A. Consider the following sets of parallel reactions taking place in the same reactor: A B2C A+B D Reaction (i) Reaction (ii) Kinetics study showed that reaction (i) proceeds at the rate of 0.1 moles per hour (reduction for A and B). On the other hand reaction (ii) proceeds at the rate of 0.2 moles per hour (reduction for A and B and production for D. i. State the overall rate of reaction of the system as a whole. ii. iii. Assuming the reaction rates stay constant how many moles of C and D are produced after 6 hours of reaction? Assuming the reaction rates stay constant how many moles of A and B are removed after 6 hours of reaction? 2B. List the six sequential steps that occur in a typical heterogeneous chemical reaction. 2C. Plot a profile of tracer salt concentration versus time for i) plug low reactor and ii) completely mixed flow reactor assuming that a tracer of known mass is added to the inlet of the reactor and the tracer salt concentration at the outlet flow is being measured with time after addition of the tracer salt. Initially the reactor flow has negligible concentration of the tracer salt. Assume that the retention time of the reactor is T Volume/flow rate. = 2D. An ion exchange resin that weighs 200 kg is employed for the removal of calcium from a given hard water, the concentration of calcium in the raw water to be treated is 400 mg/L. The ion exchange resin treats the water so that the treated water contains only 20 mg/L of Calcium. If a total of 60,000 liters water were treated, what will be the ion exchange resin capacity? 2E. State the advantages and disadvantages of choosing ion exchange media that has greater affinity for the ions to be exchanged. Page 4 of 8
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Transcribed Image Text:EHS 429 MAIN EXAMINATION PAPER 2018 DECEMBER
QUESTION TWO (5 Marks each)
2A. Consider the following sets of parallel reactions taking place in the same reactor:
A B2C
A+B D
Reaction (i)
Reaction (ii)
Kinetics study showed that reaction (i) proceeds at the rate of 0.1 moles per hour
(reduction for A and B). On the other hand reaction (ii) proceeds at the rate of 0.2 moles
per hour (reduction for A and B and production for D.
i.
State the overall rate of reaction of the system as a whole.
ii.
iii.
Assuming the reaction rates stay constant how many moles of C and D are produced
after 6 hours of reaction?
Assuming the reaction rates stay constant how many moles of A and B are removed
after 6 hours of reaction?
2B. List the six sequential steps that occur in a typical heterogeneous chemical reaction.
2C. Plot a profile of tracer salt concentration versus time for i) plug low reactor and ii)
completely mixed flow reactor assuming that a tracer of known mass is added to the
inlet of the reactor and the tracer salt concentration at the outlet flow is being
measured with time after addition of the tracer salt. Initially the reactor flow has
negligible concentration of the tracer salt. Assume that the retention time of the
reactor is T Volume/flow rate.
=
2D. An ion exchange resin that weighs 200 kg is employed for the removal of calcium from a
given hard water, the concentration of calcium in the raw water to be treated is 400 mg/L.
The ion exchange resin treats the water so that the treated water contains only 20 mg/L of
Calcium. If a total of 60,000 liters water were treated, what will be the ion exchange resin
capacity?
2E. State the advantages and disadvantages of choosing ion exchange media that has
greater affinity for the ions to be exchanged.
Page 4 of 8
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