Post Test – Day 2

This law states that when a radiation beam passes into a medium of different refractive index, not only does its wavelength change, but also its direction does

A 10mm diameter tube is covered with a 2mm thick cellular glass insulation, k=0.055 W/mK, the outer surface convection coefficient is 5 W/m² Determine if the insulation is effective?

Water at 20^oC with a mass flow rate of 5 kg/s enters a circular tube of 5 cm ID and 10m long. If the tube surface is maintained at 80^oC, determine the exit temperature of the water.

A 0.5m diameter pipe (e=0.90) carrying steam has a surface temperature of 500 K. The pipe is located in a room at 300 K., and the convection heat transfer coefficient between the pipe surface and the air in the room is 20 W/m² Calculate the rate of heat loss per meter of pipe length

What is the cooking time required to raise the center of a spherical, 8-cm-diameter dumpling from 20 to 80°C. The initial temperature is uniform. The dumpling is heated with saturated steam at 95°C. The heat capacity, density, and thermal conductivity are estimated to be c = 3500 J/(kg ⋅ K), ρ = 1000 kg/m³, and k = 0.5 W/(m ⋅ K), respectively.

By principles of convection, the fastest way to cool a can of soda in the refrigerator is by:

An evaporator is to concentrate 10% wt caustic soda solution to 50% wt. Feed enters at 100^oF and steam is available saturated at 50 psig and the evaporator can be operated at 9.96 psi vacuum, the OHTC of the evaporator is 500 BTU/h ft^{2 o}F, for the production of 10,000 lb/h of the 50%wt NaOH, what is the heating area and steam economy?

A hot solution containing 5000 kg of Na₂CO₃ and water with a concentration of 25% wt Na₂CO₃ is cooled to 293K and crystals of Na₂CO₃ 10H₂O are precipitated. At 293K, the solubility is 21.5 kg anhydrous Na₂CO₃ per 100 kg water. Calculate the yield of Na₂CO₃ crystals obtained if 5% of original water in the system evaporates on cooling

Helium and nitrogen gas are contained in a conduit 5mm in diameter and 0.1 m long at 298K and uniform constant pressure of 1.0 atm abs. The partial pressure of He at one end of the tube is 0.060 atm and the other end is 0.020 atm. Use the diffusivity of 0.687 x 10^-4 m²/s. What is the flux of He and N₂?

Ammonia gas is diffusing through N₂ under steady state conditions with N₂ diffusing that is, both boundaries are permeable to both gases and the flux is equimolar countediffusion. The total pressure is 1.013 x 10⁵ Pa and the temperature is 298K. The partial pressure of ammonia at one point is 1.333 x10⁴ Pa and a point 20mm away is 6.666 x10³ Given that the diffusivity is 2.30 x10^-5 m²/s. Calculate the flux of ammonia in kmol/m² s

Water at 83 liters/sec is flowing inside a 6inch schedule 30 nominal pipe. What is the maximum velocity In ft/s of the water at room temperature.

At very low velocities of small particles in a fluid, what causes the wall shear?

If momentum transfer is analogous to conductive heat transfer resulting from a temperature gradient, where thermal conductivity is the proportionality factor between heat flux and temperature gradient, what then is the proportionality factor between momentum flux and the velocity gradient?

The power requirement of a 3-stage compressor in hp to supply air at 90 °C at a rate of 1200 m³/hr at a total discharge pressure of 400 psig is ___ if the efficiency of the compressor is 65%.

A 30° inclined manometer is used to measure the pressure drop between two taps carrying water with 40-in distance inclined by 20°. The manometer fluid is an oil with a specific gravity of 1.92 and the manometer reading is 8 in. What is the pressure difference in psi between the two pipe taps if the manometer tubing is 1/4 in in diameter?

Which of the following continuous filters cannot be used if the cake growth rate is relatively fast?

In operating a batch filter, which of the following is the correct method of operation?

A leaf filter is used to filter a compressible sludge with s = 1.08 at 3.75 atm for 65 minutes. Washing is done at 20 psi with wash water equal to 25% of the filtrate volume collected. The washing time is

Which of the following media can be used if concentrated sulfuric acid or sodium hydroxide is required to be filtered?

The capacity of a rotary drum filter will change by a factor of ___ if the submerged area is doubled with the speed and pressure remaining the same.

For the diffusion of solute A through a layer of gas to an absorbing liquid with y_A = 0.20 and y_Ai = 0.1, what is the value of y_A halfway through the layer for one-way diffusion?

How long will it take to evaporate 5 in of unknown liquid at 75 °F (density = 125 lb_m/ft³, MW = 130) in a 10-ft diameter full, open atmospheric tank if the vapor pressure of the liquid at 75 °F is 1.65 psia and D_AB is equal to 0.025 ft²/hr?

The equimolar MTC is 8.134 × 10^-9 kg mol/s-m²-Pa at 75 °C and 1 m Hg. If y_A,1 is 0.33 and y_A,2 is 0.0056, what is the unicomponent MTC in lb mol/hr-ft²-mol fraction?

Which of the following has the highest mass diffusivity?

The diffusivity of methanol in air at 20 °C and 3.25 atm is 0.555 ft²/hr. The diffusivity of air in methanol at 100 °C and 1 atm is

Which of the following binary mixtures has the best separation via distillation at 200 °F and 1000 psia?

525 mol of solution containing 320 mol of A and the rest B is subjected to simple batch distillation. The distillate containing 245 mol A is obtained. If A is 3 times more volatile than B, the concentration of A in the distillate is

Which of the following binary solutions will NOT have a minimum boiling azeotrope?

What is the relative volatility of propane in heptane at 180 °F and 1000 mm Hg absolute?

The approximate minimum number of stages for a binary system with a relative volatility of 1.25, fractionally distilled to yield compositions of 0.95 in the distillate and 0.05 in the bottoms is

Which of the following configurations will give the minimum number of stages to accomplish a specified separation via distillation?

A packed absorption tower has straight operating line and equilibrium curve with a Henry’s constant of 2.81 and without heat effects. What is the number of overall gas-phase mass transfer units if Y₁ = 0.25, Y₂ = 0.05, and X₂ = 0.01 if L_M/G_M is 4?

What dimensionless number compares the rate of reaction in a liquid film to the rate of diffusion through the film?

Which of the following factors generally favor trays compared to random packings?

To maintain a constant pressure drop in a gas absorption column with structured packings, the flow parameter should be increased while the capacity parameter

The interfacial concentration y_i in a gas absorber corresponding to y = 0.10 mole fraction is ___ mole fraction. The slope of the operating line is 8.4 with the mole ratios Y₁ = 0.33, Y₂ = 0.01, and X₂ = 0. The equation of the equilibrium curve is y = 4.2x while the MTC’s are k_xa = 132 and k_ya = 22 lbmol/ft²-hr-mole fraction.

If 50 lb of dry air at 80°F dry bulb and 65°F wet bulb is mixed with 500 lb of dry air at 100°F dry bulb and 80°F wet bulb, what is the wet bulb temperature of the resulting mixture?

A mixture of nitrogen and acetone is at 60°C dry bulb temperature with an absolute humidity of 0.025. Calculate the other main parameters for the mixture. What is the mixture’s wet bulb temperature if system pressure is 0.1 bar absolute?

Which of the following is TRUE regarding organic solvents?

Determine the theoretically required KaV/L value for a cooling duty from 104°F inlet water, 79°F outlet water, 68°F ambient wet bulb temperature, and an L/G ratio of 1.45.

The tons refrigeration needed to supply air in a room 3 m by 3 m by 10 ft charged every 0.25 hr at 65°F dry bulb and 50% RH by cooling outside air at 35°C dry bulb and 30°C wet bulb.

The flow of liquid through the interstices and over the surface of a solid, caused by liquid-solid molecular attraction.

The moisture content of cellular materials (e.g., wood) at which the cell walls are completely saturated while the cavities are liquid-free. It may be defined as the equilibrium moisture content as the humidity of the surrounding atmosphere approaches saturation.

The resistance of a material to bulk or convective, pressure-driven flow of a fluid through it.

Ratio of free moisture remaining to that initially present

If the filter medium does not exert any resistance in the filtration process, the volume that will be collected would be:

For the elementary reaction , which of the following changes in concentration will yield the greatest increase in reaction rate?

For which types of reactions is half-life not a function of original reactant concentration?

The zeroth order reaction  takes 10 minutes to complete at 25°C. At what temperature will it take 5 minutes to complete?

Which of the following statements about catalysts is not correct?

The solubility of dibasic potassium phosphate in water at 25°C is _____parts per 100 parts water.

The terminal settling velocity in water at 70°F of a particle with a specific gravity of 2.0 and diameter of 100 microns is ____ft/s

The mass fraction of solute in the underflow is ___________ if X = 0.401 kg solute / kg solution and R = 0.631 kg solution retained per kg inert solids

The rotational speed in revolutions per minute that you could recommend for a ball mill, 1,200 mm in diameter charged with 75 mm balls is

If a centrifuge is 0.9 m diameter and rotates at 20 Hz, the speed of a laboratory centrifuge of 150 mm diameter be ran if it is to duplicate plant conditions is

Choke crushing (in case of a jaw crusher) compared to free crushing

The surface area and sorptive capacity of silica gel adsorbent are between ______km²/kg dry solid and between ______ kg/kg dry solid respectively

The change in enthalpy per unit weight of adsorbed gas when adsorbed on gas free or “outgassed” adsorbent to form a definite concentration of adsorbate is called its

Which of the following is the most suitable for cleaning of fine coal dust (< 0.5 m)?

When the solvent dissolves very little of solute then

Paper pulp produced by kraft/sulphate process is

Gold is frequently recovered from its ore by forming a water soluble complex with

The gasification reaction represented by, C + H₂O = CO + H₂, is a/an __________ reaction.

Concentration of hydrogen peroxide is done by

The Bayer process for purifying bauxite relies upon the

The response of two tanks in series is

In case of bubble cap distillation column of diameter greater than 1.2 metres, the cap diameter is roughly about __________ cms.

Joint efficiency for a seamless pipe is

In case of a shell and tube heat exchanger, the minimum shell thickness for carbon steel (inclusive of corrosion allowance) depends on shell diameter and is in the range of __________ mm.

A laboratory short-tube vertical evaporator is used to boil sugar juices at 57°C with a temperature difference of 20 R°. Estimate the overall heat transfer coefficient in BTU/ft²-hr-F° if the solution has a viscosity of 3.0 cP

Which of the following is a common assumption regarding the design of multi-effect evaporators?

If the to be evaporated tends to severely scale, the type of evaporator to be recommended with small capacity needed is

Estimate the friction pressure drop in a long-tube vertical evaporator if the entering liquid has a pressure drop of 0.1 psi and the exiting vapor has a quality of 90%. The equipment evaporates water at atmospheric pressure with negligible boiling point rise.