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Unformatted text preview: #1 (20 points) a) (7 pts) The Thiele modulus (M T ) is an important number for assessing transport limitations in porous catalysts. For a first order reaction is given by: L = characteristic length k = rate constant D eff = diffusion constant Calculate the Thiele modulus for a catalyst with a characteristic length of 2 mm, a rate constant of 0.5 min1 , and a diffusion constant of 0.08 cm 2. s1 . M T = 2 mm (0.1 cm/1 mm) . . M T = 0.065 b) You are taking your car to a gas station to check the pressure of your tires and measure a gauge pressure of 32 psi. What is the absolute pressure in your tire in atmospheres? P = (32 lb f /in 2 ) (14 lb f /in 2 /1 atm) + 1 atm P = 3.2 atm c) (9 pts) John empties his bladder after a long morning of working outside. Following 24 fl oz. of water, John eats 3 slices of pizza and drinks two beverages over the next 2 hours. The table below summarizes his consumption. Product Weight or Volume % Water content Water 24 fl oz. 100 Pizza, 3 slices 0.5 kg / slice 20 Coke 8 fl oz. 100 Sprite 4 fl oz. 100 On a splendid day with moderate temperature and low humidity, John perspires at a rate of 0.1 mL/m 2 /min. After 2 hrs John goes again to empty his bladder. Determine the amount of liquid excreted to return John to the state he was at prior to eating and drinking. Assume that the total liquid in his body does not change and that the average area of human skin is 2 m 2 . Simple mass balance In = Out (Specify V as unknown volume excreted) Water + Pizza + Coke + Sprite = Amount perspired + Amount excreted 24 oz + (3 slices 0.5 kg/slice 0.2 / water ) + 8 oz + 4 oz = [0.1 ml/(m 2 min) 120 min x 2 m 2 ] + V 36 oz (29.57 ml/oz) + (0.3 kg 0.001m 3 /1 kg (0.1 3 cm 3 /1 3 m 3 ) (1 ml/ 1 cm 3 )) = 0.1 ml/( m 2 min) 120 min 2 m 2 + V V = 45.32 oz = 1340.5 ml #2 (20 pts) a) (7 pts) Consider the following flow chart for a process for the reaction A B: Compare the singlepass conversion and the overall conversion qualitatively (i.e. which one is higher). Provide an explanation for your answer....
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 Summer '08
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 Catalyst, Reaction

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