Science

4. (20 pts.) Below is a liquid-solid phase diagram for a mixture of two components, A and B. 700 T(K) 800 750 p liquid 650 600 550 500 450 400 40 350 300 0 01 02 03 04 05 06 07 08 09 1 24 (a) For the points labeled 1 through 4 along the vertical line at 20.2, provide the number of phases pret a description of each phase, and the mole fraction of B in each phase. (To receive full credit, descriptions must be clear and unambiguous.) I (b) What is the melting temperature of pure A? © What is the melting temperature of pure B? (d) What is the eutectic temperature? (e) What is the eutectic composition? ( What is the freezing point of a liquid with 2-0.27 (C) For the two-component system described by the phase diagram in problem #4, sketch cooling curves for solutions with Zp = 0,25 = 0.2, and zp = 0.4. The cooling curves should start at 800 K. What quantity does the horizontal axis correspond to?

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The Environmental Protection Agency (EPA) wants to restrict the amount of pollutants added by a company to the river water. The concentrations of phenol and nitrogen in the water are to be restricted to, respectively, P and N lbs. MG (million gallons) on a daily basis. The river has a flow of M MG/day. The company diverts a portion of the river water, adds the pollutants, namely, phenol and nitrogen, to it, and sends the water back to the river. The company has four possible ways to treat the water it uses before returning it to the river. The characteristics of each treatment are given in the following table:

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The Environmental Protection Agency (EPA) wants to restrict the amount of pollutants added by a company to the river water. The concentrations of phenol and nitrogen in the water are to be restricted to, respectively, P and N lbs. MG (million gallons) on a daily basis. The river has a flow of M MG/day. The …

The Environmental Protection Agency (EPA) wants to restrict the amount of pollutants added by a company to the river water. The concentrations of phenol and nitrogen in the water are to be restricted to, respectively, P and N lbs. MG (million gallons) on a daily basis. The river has a flow of M MG/day. The company diverts a portion of the river water, adds the pollutants, namely, phenol and nitrogen, to it, and sends the water back to the river. The company has four possible ways to treat the water it uses before returning it to the river. The characteristics of each treatment are given in the following table: Read More »

1. In a water to air heat exchanger, it is important to place fins on the air side because a. The air side heat transfer coefficient is so much lower than on the water side. b. It reduces drag in high speed flows c. The air side heat transfer coefficient is higher than that of the water side d. It affects good mixing of the gas and this promotes good heat transfer 2. In a heat exchanger, when is the heat transfer maximum? a. T(cold inlet) = T(hot inlet) b. T(cold inlet) = T(cold outlet) c. T(cold outlet) = T(hot outlet) d. The equipment is new 3. Which of the following a measure of the performance of an evaporator? a. Heat transfer rate b. Steam economy c. Heat transfer coefficient d. Heating surface area 4. Which of the following is most likely the effect of lowering the feed temperature in an evaporator? a. Decreased heating area requirement b. Reduced steam consumption c. Reduced steam economy d. Increased capacity 5. A greater wall thickness of the packing material (i.e. Raschig Rings) will result a / an a. Decreased superficial velocity b. Greater free space c. Increased surface area d. Increased pressure drop 6. Which of the following is TRUE as regards to gas absorption? a. The operating line is always straight b. The operating line is below the equilibrium line c. The operating line represents a heat balance d. For efficient mass transfer, the resistance in the liquid film should be low.

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EXPERT ANSWER 1)a) option is the right answer. Fins are used to increase heat transfer where heat transfer coefficient is low by increasing effective heat transfer area. This statement supports first option is the best choice. 2) d) option is correct heat transfer rate Q is directly proportional to heat transfer coefficient(U), effective area(A) and …

1. In a water to air heat exchanger, it is important to place fins on the air side because a. The air side heat transfer coefficient is so much lower than on the water side. b. It reduces drag in high speed flows c. The air side heat transfer coefficient is higher than that of the water side d. It affects good mixing of the gas and this promotes good heat transfer 2. In a heat exchanger, when is the heat transfer maximum? a. T(cold inlet) = T(hot inlet) b. T(cold inlet) = T(cold outlet) c. T(cold outlet) = T(hot outlet) d. The equipment is new 3. Which of the following a measure of the performance of an evaporator? a. Heat transfer rate b. Steam economy c. Heat transfer coefficient d. Heating surface area 4. Which of the following is most likely the effect of lowering the feed temperature in an evaporator? a. Decreased heating area requirement b. Reduced steam consumption c. Reduced steam economy d. Increased capacity 5. A greater wall thickness of the packing material (i.e. Raschig Rings) will result a / an a. Decreased superficial velocity b. Greater free space c. Increased surface area d. Increased pressure drop 6. Which of the following is TRUE as regards to gas absorption? a. The operating line is always straight b. The operating line is below the equilibrium line c. The operating line represents a heat balance d. For efficient mass transfer, the resistance in the liquid film should be low. Read More »

6. A body is dropped from a height of 300ft with an initial velocity of 30 ft /sec. Assuming no air resistance, (a) find an expression for the velocity of the body at any time t; (b) find the time r(1u1red for the body to hit the ground. 7. A ball is propelled straight up with an initial velocity of 250 ft/sec in a vacuum with no air resistance. How high will it go ?

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EXPERT ANSWER 6) a) V = U + g*t where U – initial velocity b) h = ut + .5gt^2 300 = 30t + .5* 32.17*t^2 t = 3.49 sec 7) h = u^2 /2g = 250^2/(2*32.17) = 971.4 ft

Five grams of an organic solid is dissolved in 100 ml of H20 (solvent 1). Which of the following extraction methods will remove the largest amount of the organic solid from the aqueous solution? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a Three 50 ml portion extractions with ether (solvent 2) b Two 50 ml portion extractions with ether (solvent 2) с One 150 ml portion extractions with ether (solvent 2) d One 50 ml portion extractions with ether (solvent 2) o Q.7.2-Post-Lab Caffeine Extraction Homework. Unanswered The pka of 2,5-dinitrophenol is 5.15. Will it dissolve in sodium carbonate solution? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a No, typically organic phenols do not dissolve i aqueous solution b No, because the 2,5-dinitrophenolis basic с Yes, the 2,5-dinitrophenol will react with sodium carbonate, and the resulting salt will dissolve in aqueous solution d Yes, any phenol is soluble in sodium carbonatelution

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EXPERT ANSWER Organic extraction Ans: a) Three 50mL extraction with ether (solvent 2). The multiple extraction is effective than the bulk single extraction. Hence Three 50mL would be best. 2,5-Dinitro phenol: Ans: C The 2,5-Dinitrophenol pKa = 5.5, Hence it will react with Sodium bicarbonate (pKa of HCOO– = 6.4, higher than pKa of 2,5-Dinitro phenol) …

Five grams of an organic solid is dissolved in 100 ml of H20 (solvent 1). Which of the following extraction methods will remove the largest amount of the organic solid from the aqueous solution? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a Three 50 ml portion extractions with ether (solvent 2) b Two 50 ml portion extractions with ether (solvent 2) с One 150 ml portion extractions with ether (solvent 2) d One 50 ml portion extractions with ether (solvent 2) o Q.7.2-Post-Lab Caffeine Extraction Homework. Unanswered The pka of 2,5-dinitrophenol is 5.15. Will it dissolve in sodium carbonate solution? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a No, typically organic phenols do not dissolve i aqueous solution b No, because the 2,5-dinitrophenolis basic с Yes, the 2,5-dinitrophenol will react with sodium carbonate, and the resulting salt will dissolve in aqueous solution d Yes, any phenol is soluble in sodium carbonatelution Read More »