The elementary irreversible gas phase reaction A --> B + C is carried out in a PFR packed with catalyst. Pure A enters the reactor at a volumetric flowrate of 20 dm³ /s at a pressure of 10 atm and 450K. Consider that the heat is removed by a heat exchanger jacketing the reactor. The flowrate of coolant through the jacket is sufficiently high so that the ambient exchanger temperature is constant at 50^oC.

C_pA=40 J/mol.K HfA=-70 kJ/mol

C_pB=25 J/mol.K H_fB=-50 kJ/mol   (T_R=273 K)

C_pC=15 J/mol.K H_fC=-40 kJ/mol

k = 0.133 exp (E/R [ 1/450 ? 1/T ]) dm³ kg cat. s with E = 31.4 kJ/mol

U= 100 W/m2 .K

D_t=10 cm

p_b=5 g/cm3

a) Plot the conversion and temperature down the plug flow reactor until 80% conversion is achieved. Discuss the effect of feed temperature on the temperature profile and conversion.

b) Calculate the amount of catalyst required to achieve 80% conversion.

Electrical power is to be produced from a steam turbine connected to a nuclear reactor. Steam is obtained from the ractor at 540 K and 36 bar, the turbine exit pressure is 1.0 bar, and the turbine is adiabatic.

a) Compute the maximum work per kilogram of steam that can be obtained from the turbine.

A clever chemical engineer has suggested that the single-stage turbine considered here be replaced by a two-stage adiabatic turbine, and that the steam exiting from the first stage be returned to the reactor and reheated, at constant pressure, to 540 K, and then fed to the second stage of the turbine.

b) Compute the maximum work obtained per kilogram of steam if the two-stage turbine is used and the exhaust pressure of the first stage is 0.5(36 + 1) = 18.5 bar.

c) Compute the maximum work obtained per kilogram of steam if the two-stage turbine is used and the exhaust pressure of the first stage is sqrt(36 x 1) = 6 bar.

d) Compute the heat absorbed per kilogram of steam in the reheating steps

A) A sealed container initially contains only 1.0 M gas A and 1.0 M gas B. Upon heating the following reaction takes place: A(g) + 2 B(g) ? C(g)+ 2 D(l). After the reaction comes to equilibrium, the concentration of gas C is 0.25 M. What is the equilibrium constant K_c for this reaction?

B). The decomposition of N₂O₄ into NO₂ has K_p = 2. Some N₂O₄ is placed into an empty container, and the partial pressure of NO₂ at equilibrium is measured to be 0.2 atm. What was the initial pressure in the container prior to decomposition?

C). For the following reaction, find the value of Q and predict the direction of change, given that a 1L flask initially contains 2 moles S₈, 2 moles SF₆, and 2 moles F_2.               

1/8 S₈ (s) + 3 F₂ (g) ? SF₆ (g)   K_c = 0.425

D)

A key step in the extraction of iron from its ore is

FeO(s) + CO(g) ? Fe(s) + CO₂(g) K_p =0.403 at 1000°C.

What are the equilibrium partial pressures off carbon monoxide and carbon dioxide when 1.00 atm of carbon monoxide and excess iron(II) oxide react in a sealed container at 1000°C.

Explain step by step how to determine whether the exchanger is suitable for the duty, how to estimate the pressure drop for each stream.

In isolation, a DNA-binding protein binds to its regulatory sequence with a Kd of 1.0 microM. Another DNA binding protein binds to another sequence on the same DNA a few bases away with a Kd of 5.0 microM when alone. The two proteins each have a domain which binds to the other, with an interaction energy of -2.7 kcal/mole: (a) Draw the thermodynamic box which represents all four states of this system. (b) what are the affinities for each protein in the presence of saturating amounts of the other?

Below are a few paragraphs from Tough’s essay, “Who Gets to Graduate?” Please read each paragraph carefully. Then write a 1-2 sentence summary for each portion of the reading. “Listen” carefully to what Tough is saying and try your best to capture his argument.

…whether a student graduates or not seems to depend today almost entirely on just one factor — how much money his or her parents make. To put it in blunt terms: Rich kids graduate; poor and working-class kids don’t…When you read about those gaps, you might assume that they mostly have to do with ability…But ability turns out to be a relatively minor factor behind this divide.

Tough believes the student

[The University of Texas’] efforts are based on a novel and controversial premise: If you want to help low-income students succeed, it’s not enough to deal with their academic and financial obstacles. You also need to address their doubts and misconceptions and fears. To solve the problem of college completion, you first need to get inside the mind of a college student…“There are always going to be both affluent kids and kids who have need who come into this college,” Laude said. “And it will always be the case that the kids who have need are going to have been denied a lot of the academic preparation and opportunities for identity formation that the affluent kids have been given…”

Tough believes…

When you send college students the message that they’re not smart enough to be in college — and it’s hard not to get that message when you’re placed into a remedial math class as soon as you arrive on campus — those students internalize that idea about themselves.

Tough believes…

To the extent that the Stanford researchers shared a unifying vision, it was the belief that students were often blocked from living up to their potential by the presence of certain fears and anxieties and doubts about their ability. These feelings were especially virulent at moments of educational transition — like the freshman year of high school or the freshman year of college. And they seemed to be particularly debilitating among members of groups that felt themselves to be under some special threat or scrutiny: women in engineering programs, first-generation college students, African-Americans in the Ivy League.

Tough believes…

The negative thoughts took different forms in each individual, of course, but they mostly gathered around two ideas. One set of thoughts was about belonging. Students in transition often experienced profound doubts about whether they really belonged — or could ever belong — in their new institution. The other was connected to ability. Many students believed in what Carol Dweck had named an entity theory of intelligence — that intelligence was a fixed quality that was impossible to improve through practice or study.

Tough believes…

Read your summaries again. Then, in one sentence, write here what you believe Tough is arguing in your section of his essay.

Tough argues that…

You separated a mixture containing 20 wt% CH3OH, 35 wt% C2H5OH, and the balance water into two fractions. You then drew and analyzed samples of both product streams and reported that one stream contained 42.2% CH3OH and 29.3% C2H5OH and the other stream contained 16.5% CH3OH and 45.2% C2H5OH. After examining the report your professor indicated that the results must be wrong and asked you to repeat the stream analyses. Show why the professor is right

Your truck transports ethylene to customers at - 200°F and 1 atm pressure. How manylb's of ethylene will it take to fill up a customers 100 ft3 tank to a final pressure of 1000psia and a final temperature of 70°F? (Tc= 283.1 K, Pc= 50.5 atm)

ANSWER IS 1400 lb. Please show steps to get answer.

Hydrogen may be the fuel of the next generation. Why would hydrogen be used in a fuel cell to make electricity rather than in a combustion engine?

Classify desalination technologies according to “Separation method” and “Driving force”. Give examples.

Explain the phenomenon of concentration polarization in ED systems (i.e. depletion of ions….etc). What should be done to minimize fouling? and define current density, and CD/N ratio. How is CD/N ratio related to concentration polarization in ED systems?

Compare porous vs non-porous membranes with respect to water diffusion mechanism, pressure difference. Give examples on both types.

Define salt rejection, salt passage, and water recovery.

What is the difference between membrane fouling and membrane degradation? Classify membrane fouling (i.e. biofouling, organic, and inorganic) and suggest cleaning methods.