A solution containing 35% by mass of Glauber salt, Na2SO4 is cooled down from 323 K to 298 K in a Swenson-Walker crystalliser to form crystals of Na2SO4•10H2O. The solubility of Na2SO4at 298 K is 13.9 kg/100 kg of water, and the required product rate of crystals is 0.1 kg/s. The molecular mass of the anhydrous and hydrated salt is 142 kg/kmol and 322 kg/kmol, respectively. The mean heat capacity Cp of the solution is 2 kJ/(kg K), and the heat of crystallisation is 150 kJ/kg. The cooling water enters and leaves at 285 K and 293 K, respectively, and the overall coefficient of heat transfer is 125 W/m2 K. Assume counter- current flow and that 3% of the initial solution is evaporated.

(i) State the general equation for the calculation of the crystal yield and define the variables used.

(ii) Calculate the crystal yield.
(iii) Calculate the required feed to produce 0.1 kg/s of crystals. (iv) Calculate the heat required to cool the solution.

(v) Calculate the heat of crystallisation and the total heat required. (vi) Calculate the required heat transfer area.

Define reflux ratio and explain its importance in distillation process. (4)

4.2. Explain how the reflux ratio affects number of stages in the distillation column. (4)

4.3. State six conditions of the nature of feed for fixed reflux ratio. (6)

4.4. List six scenarios when liquid-liquid extraction is preferred over distillation. (6)

What are the different types of drug carrying vehicles used for delivering drug in Nanotechnology. Describe briefly about Core-Shell Nanostructures?

1- a) Determine the expansion work performed when 10.0 g of hydrogen is burned at 1.01 bar and 2800 ° C.
b) Explain what the effect would be on the expansion work if one were to count at 1 bar and 25 ° C instead? Don't forget to justify your answer!

From a control process, what is the effect of an overshoot in products composition in a distillation column?

can it be concluded that it is a consequence of an overshoot in temperature inside the column?

1. In carbonitriding of an iron-carbon alloy (steel) initially containing 0.05 wt% C and no nitrogen is subjected to carbonitriding at an elevated temperature and in an atmosphere that gives a surface carbon concentration constant at 0.5 wt% and surface nitrogen concentration constant 0.2 wt%. Find the ratio of the diffusion coefficients ‘C in steel’/‘N in steel’ if after 36 h the concentration of carbon at a position 0.4 mm below the surface is 0.35 wt%, and the concentration of nitrogen at the same depth is 0.10 wt%.

2. Using your knowledge on diffusion mechanisms in solids, would you expect the ratio ‘C in steel’/‘N in steel’ you found in (1) ? (Would you expect DC in steel or DN in steel to be larger?) 3. Sketch expected trends for: a) the concentration of carbon vs depth and the concentration of nitrogen vs depth (on the same graph), b) overall density vs depth, c) the number of substitutional vacancies vs depth.

4. What is the temperature in (1)? Qd for C in steel is 148 J/mol and Do = 2.3 x 10-5 m2 /s 5. In cyaniding, another case-hardening process, carbon source is NaCN. The part to be hardened is heated above 850 C is immersed in a bath of aqueous NaCN. The process produces more efficient diffusion of carbon in just 20-30 min. In comparison to carburization - which takes hours for depositing same amount of carbon at the same depths – cyaniding seems more cost-effective. However, it is not widely used, why? 6. Write down two applications of case-hardening

A Carnot heat engine operates between temperature levels of 600 K and 300 K with 8 MW heat transferred in the boiler. It drives a compressor, which compresses steam from 200 kPa, 200°C to 1 MPa, 500°C. If mass flow rate of the steam is 5 kg/s. determine the following:

(a) The power output of the heat engine (kW).

(b) The power input of the compressor (kW).

(c) The efficiency of the compressor.

A centrifugal pump is to be used to pump water from a lake to a storage tank which is 165 feet above the surface of the lake. The pumping rate is to be 10 - 35 gal/min at a water temperature of 43°F. The water is used for drinking but will have to undergo filtration and chlorine treatment because there is sediment in the lake. The pump on hand can develop a discharge pressure of 60.0 psig pumping at a rate of 40.0 gal/min through a 2 inch schedule 40 pipe. a) How much power does the pump develop? b) Is it sufficient for the task? Why or why not? c) Is the pipe chosen thick enough?

A really important chemical (D) is produced from available feedstock (A) in liquid phase reaction. At reaction conditions, A also degrades into undesirable impurity (U). The reactions are given as: A D rD = k1C 2 A A U rU = k2CA The reaction is carried out in two CSTRs with residence times of 2.5 min and 10 min respectively connected in series. The feed to the first reactor contains A and U with concentrations of CA0= 1.0, and CU0 = 0.3 (units are not important). At the end of first reactor, following composition is obtained: CA1 = 0.4 CD1 = 0.2 CU1 = 0.7 Find the composition leaving the second reactor.

A cylinder of 10-m-high, and a cross-sectional area of 0.1 m2 , has a piston (that is free to move) assumed to have negligible mass and thickness (see Figure 1(a)). Above the piston there is a liquid that is incompressible (constant density and volume) with ρliquid = 1000 kg/m3 . Below the piston there is air at 300 K, with a volume of 0.3 m3 . Assume air is an ideal gas (Ru =8.314 J.mol-1 .K-1 ; Mair = 28.9628 g/mol) Use P0 = 101.325 kPa and g = 9.807 m/s2 Find the following: a- The mass (in kg) of the liquid in the cylinder. b- The initial pressure of the air compartment. c- The initial mass of air (in kg). d- The initial internal energy of air. Another negligible mass and thickness piston is placed on top of the cylinder (see Figure 1b) and pushed down by 0.1 m to compress the air. The process is isothermal. The liquid is incompressible (its volume and phase do not change). Calculate: e- The final volume of air. f- The final temperature of air when thermal equilibrium is obtained. g- The final pressure of air. h- Does the internal energy of air change? i- The boundary work used to lower the piston located on top of the air. j- The total heat transfer outside of the piston from the air compartment.

A packed bed reactor with present of catalyst: A_(g) + 0.5 B_(g) --> C(g) . . -r_A’ = k C_A^0.33C_B^0.66 . A student is tasked with designing the reactor and predicting the output. The student forgets to take into account the effects of pressure drop on the design. For a packed bed reactor with 100 g of catalyst, the exiting concentration of C that the student determines is likely to be equal/ greater than the exiting concentration that is predicted to exist if pressure drop is taken into account. Explain? (Less than is wrong)

Identifying terms: (HINT: think “who, what, when, where and why?”)

Treaty of Tordesillas

The Great Schism

Please select one of casting methods which you think is the most suitable for the following object and give a description why you make this selection

1. Titanium hip joint                                    
2. Engine block of a motor car                                                  
3. a scale model toy car                                                       
4. Large steel sheet                                      
5. Pipes/tubing