CENEVAL EGEL Plus Ingeniería Química (EGEL Plus IQUIM)

A continuous chemical process receives a fresh feed of 100 mol/h of compound A containing 2.0 mol% of an inert gaseous impurity I. The reactor achieves a single-pass conversion of 20% of A. Unreacted A and inert I from the reactor separator are recycled, but a purge stream containing 10.0 mol% of inert I is withdrawn to prevent accumulation. What is the required molar flow rate of the purge stream at steady state?

• A10.0 mol/h
• B20.0 mol/h
• C50.0 mol/h
• D2.0 mol/h

A fresh fruit juice stream of 1,000 kg/h containing 10.0 wt% soluble solids is concentrated using an evaporator. To preserve volatile aroma compounds, a bypass stream is split from the fresh juice before the evaporator and blended downstream with the evaporator discharge (which leaves at 58.0 wt% solids). If the final blended product must contain exactly 42.0 wt% solids, what is the required bypass flow rate?

• A761.9 kg/h
• B42.0 kg/h
• C79.4 kg/h
• D158.8 kg/h

Propane (C3H8) is burned completely with 20.0% excess dry air in a process furnace according to the stoichiometry C3H8 + 5 O2 -> 3 CO2 + 4 H2O. Air consists of 21.0 mol% O2 and 79.0 mol% N2. What is the mole fraction of O2 in the dry flue gas leaving the stack?

• A3.76%
• B3.27%
• C2.07%
• D25.0%

A perfectly mixed holding tank initially contains 500 L of pure water. At time t = 0, a saline stream containing 0.20 kg/L of NaCl is fed to the tank at a volumetric flow rate of 10.0 L/min. Solution is simultaneously withdrawn from the tank at 10.0 L/min to maintain a constant liquid volume. Assuming constant liquid density, what is the salt concentration in the effluent stream after 50.0 minutes?

• A0.200 kg/L
• B0.074 kg/L
• C0.100 kg/L
• D0.126 kg/L

A process heat exchanger heats 2,000 kg/h of liquid water (specific heat capacity Cp = 4.184 kJ/kg·K) from 20.0 °C to 80.0 °C using saturated steam at 150 °C. The steam condenses isothermally with a latent heat of condensation lambda = 2,114 kJ/kg without subcooling. Assuming negligible heat loss to the environment, what is the required steam consumption rate?

• A118.8 kg/h
• B237.5 kg/h
• C475.0 kg/h
• D222.5 kg/h

Given the standard enthalpies of formation at 298 K: Delta_H_f°[CH4(g)] = -74.8 kJ/mol, Delta_H_f°[CO2(g)] = -393.5 kJ/mol, and Delta_H_f°[H2O(l)] = -285.8 kJ/mol, what is the standard higher heat of combustion (Delta_H_c°) for methane at 298 K?

• A-890.3 kJ/mol
• B-604.5 kJ/mol
• C-965.1 kJ/mol
• D-802.3 kJ/mol

A liquid mixture containing 40.0 mol% benzene (1) and 60.0 mol% toluene (2) is maintained in vapor-liquid equilibrium at 80.0 °C. At this temperature, the pure component vapor pressures are P1_sat = 101.3 kPa and P2_sat = 39.0 kPa. Assuming ideal solution behavior in both phases (Raoult's law), what is the total bubble point pressure and the equilibrium vapor mole fraction of benzene (y1)?

• AP = 70.15 kPa, y1 = 0.578
• BP = 140.3 kPa, y1 = 0.722
• CP = 63.92 kPa, y1 = 0.634
• DP = 63.92 kPa, y1 = 0.400

In a non-ideal binary liquid mixture at 65 °C, component 1 has a liquid mole fraction x1 = 0.15 and a pure vapor pressure P1_sat = 60.0 kPa. Due to positive deviations from Raoult's law, its activity coefficient is gamma1 = 1.80. What is the equilibrium partial pressure of component 1 in the vapor phase, assuming ideal gas behavior for the vapor?

• A9.00 kPa
• B16.20 kPa
• C108.0 kPa
• D5.00 kPa

In cubic equations of state such as van der Waals, Redlich-Kwong, and Peng-Robinson, what physical phenomena do the parameters 'a' and 'b' represent in the pressure explicit expression P = RT/(v - b) - a/(v^2 + ...)?

• AParameter 'a' accounts for attractive intermolecular forces, while 'b' represents the co-…
• BParameter 'a' represents molecular kinetic energy, while 'b' accounts for dipole orientat…
• CParameter 'a' is the critical compressibility factor, while 'b' is the acentric factor of…
• DParameter 'a' accounts for molecular size (co-volume), while 'b' accounts for attractive…

For the gas-phase chemical equilibrium reaction A(g) <=> 2 B(g) at 500 K, the standard Gibbs free energy change of reaction is Delta_G° = +5,762 J/mol. Taking the universal gas constant R = 8.314 J/mol·K, what is the thermodynamic equilibrium constant K_p at 500 K?

• A4.00
• B1.38
• C0.041
• D0.25

An industrial reversible exothermic synthesis reaction (Delta_H° = -65 kJ/mol) operates at 450 K. If the operating temperature of the reactor is increased to 520 K at constant pressure, how does the thermodynamic equilibrium constant K change according to the van 't Hoff equation?

• AK increases because higher temperatures always accelerate chemical reactions
• BK remains unchanged because K depends exclusively on total system pressure
• CK decreases because the derivative d(ln K)/dT is negative for exothermic reactions
• DK increases because the standard Gibbs free energy becomes more negative

What is the thermodynamic definition and physical significance of the fugacity coefficient (phi_i) of a species in a multicomponent gas phase?

• Aphi_i = f_i / (y_i·P), quantifying the ratio of effective thermodynamic pressure to parti…
• Bphi_i = P / f_i, quantifying the liquid vapor pressure correction at elevated pressures
• Cphi_i = gamma_i·x_i, representing the ratio of chemical potential to enthalpy
• Dphi_i = f_i / P_i_sat, representing the Poynting correction factor for condensed phases

Water at 20 °C (density rho = 1,000 kg/m³, dynamic viscosity mu = 1.00 × 10⁻³ Pa·s) flows through a commercial smooth pipe with an inside diameter D = 0.050 m at a volumetric flow rate Q = 3.534 × 10⁻³ m³/s (approx. 12.72 m³/h). What is the Reynolds number (Re) and the corresponding flow regime?

• ARe = 1,800; laminar flow
• BRe = 90,000; fully turbulent flow
• CRe = 4,500; transitional flow
• DRe = 22,500; laminar flow

A liquid with density rho = 1,000 kg/m³ flows at an average velocity v = 2.00 m/s through a horizontal pipe of length L = 100 m and inside diameter D = 0.100 m. The Darcy friction factor is f = 0.0245. Taking g = 9.81 m/s², what is the frictional head loss (h_f) and the resulting frictional pressure drop (Delta_P)?

• Ah_f = 2.50 m, Delta_P = 24.5 kPa
• Bh_f = 10.0 m, Delta_P = 98.1 kPa
• Ch_f = 5.00 m, Delta_P = 49.0 kPa
• Dh_f = 1.25 m, Delta_P = 12.3 kPa

For fully developed laminar flow of an incompressible Newtonian fluid through a straight circular pipe of diameter D, according to the Hagen-Poiseuille law, how does the pressure drop Delta_P vary with pipe diameter D at a fixed volumetric flow rate Q?

• ADelta_P is inversely proportional to D (proportional to 1/D)
• BDelta_P is inversely proportional to D^2 (proportional to 1/D^2)
• CDelta_P is directly proportional to D^4
• DDelta_P is inversely proportional to D^4 (proportional to 1/D^4)

A polymer solution behaves as a pseudoplastic (shear-thinning) fluid obeying the Ostwald-de Waele power-law model: tau = K·(gamma_dot)^n. What is the value of the flow behavior index n for such fluids, and how does the apparent viscosity (eta_app) respond as shear rate increases?

• An < 1; apparent viscosity decreases as shear rate increases
• Bn > 1; apparent viscosity increases as shear rate increases
• Cn = 1; apparent viscosity remains constant regardless of shear rate
• Dn < 1; apparent viscosity increases as shear rate increases

In a chemical plant piping system, water flows at an average velocity of 3.00 m/s through a line containing a fully open globe valve with a minor loss resistance coefficient K_L = 10.0. Taking acceleration due to gravity g = 9.81 m/s², what is the localized head loss across this valve?

• A1.53 m
• B4.59 m
• C9.17 m
• D0.46 m

A planar furnace wall consists of 0.20 m of refractory brick (thermal conductivity k1 = 1.20 W/m·K) followed by 0.05 m of thermal insulation board (k2 = 0.08 W/m·K). The inside surface of the refractory brick is at 800 °C and the outside surface of the insulation is maintained at 50 °C. What is the steady-state heat flux (q/A) through this composite wall?

• A4,500 W/m²
• B1,894 W/m²
• C947 W/m²
• D473 W/m²

A liquid is being heated while flowing in fully developed turbulent flow inside a smooth circular tube (Re = 30,000, Pr = 4.50). According to the classic Dittus-Boelter correlation Nu = 0.023·Re^0.8·Pr^n, what is the appropriate value of exponent n for heating, and what is the resulting Nusselt number (Nu)?

• An = 0.4; Nu = 160
• Bn = 0.3; Nu = 138
• Cn = 0.33; Nu = 145
• Dn = 0.5; Nu = 186

A countercurrent double-pipe heat exchanger is used to cool an organic process stream from 120 °C to 60 °C using cooling water that enters at 20 °C and leaves at 50 °C. What is the log mean temperature difference (Delta_T_lm) across the exchanger?

• A55.0 °C
• B39.1 °C
• C30.0 °C
• D53.6 °C

A tubular heat exchanger must transfer a thermal heat duty Q = 250 kW. The clean overall heat transfer coefficient is U = 500 W/m²·K, and the corrected log-mean temperature difference is Delta_T_lm = 25.0 K. What effective heat transfer surface area A is required?

• A10.0 m²
• B20.0 m²
• C0.020 m²
• D12,500 m²

An uninsulated process pipe with an outer surface area of 10.0 m² and surface emissivity epsilon = 0.85 operates at a surface temperature of 227 °C (500 K). The surrounding ambient plant walls are at 27 °C (300 K). Given the Stefan-Boltzmann constant sigma = 5.670 × 10⁻⁸ W/m²·K⁴, what is the net rate of radiative heat loss from the pipe?

• A1.28 kW
• B30.8 kW
• C26.2 kW
• D30.1 kW

Equimolar counterdiffusion of two ideal gases A and B occurs at steady state across a stagnant gas film of thickness delta = 1.00 mm (0.0010 m). At one boundary, the molar concentration of A is c_A1 = 0.050 mol/m³, while at the opposite boundary it is c_A2 = 0.010 mol/m³. If the binary diffusion coefficient is D_AB = 2.00 × 10⁻⁵ m²/s, what is the steady-state molar diffusion flux J_A?

• A8.00 × 10⁻⁴ mol/m²·s
• B1.00 × 10⁻³ mol/m²·s
• C8.00 × 10⁻⁷ mol/m²·s
• D2.00 × 10⁻⁴ mol/m²·s

In Whitman's two-film theory for interphase gas-liquid mass transfer, the overall liquid mass transfer coefficient K_L is expressed as 1/K_L = 1/k_L + H/k_G, where H is the Henry's law constant in concentration-pressure units (c_i = H·p_i). For the absorption of an extremely soluble gas such as NH3 or HCl in water (where H is very large), which phase governs the rate of mass transfer?

• ALiquid-phase film resistance completely controls the absorption rate
• BGas-phase film resistance completely controls the absorption rate
• CBoth liquid and gas films offer equal 50% resistance regardless of solubility
• DInterfacial chemical reaction kinetics controls, making film resistance negligible

In transport phenomena and dimensional analysis of mass transfer, what is the physical interpretation of the Schmidt number (Sc = nu / D_AB = mu / (rho·D_AB))?

• AThe ratio of convective heat transfer to conductive heat transfer
• BThe ratio of inertial forces to viscous forces in fluid flow
• CThe ratio of mass transfer velocity to bulk convective velocity
• DThe ratio of momentum diffusivity (kinematic viscosity) to mass diffusivity

In transport phenomena, the Chilton-Colburn analogy relates heat and mass transfer through dimensionless j-factors: j_H = St_H·Pr^(2/3) and j_D = St_m·Sc^(2/3). Under what operating conditions is the Chilton-Colburn analogy valid for turbulent boundary-layer flow?

• AIn turbulent flow with negligible form drag (skin friction dominating) over smooth geomet…
• BExclusively in creeping laminar flow through packed beds where Reynolds numbers are below…
• COnly for non-Newtonian Bingham plastics where yield stress dominates boundary layer behav…
• DOnly for pure conduction in stationary solids where convective velocity is zero

An isothermal liquid-phase first-order irreversible reaction A -> B with reaction rate constant k = 0.050 min⁻¹ is conducted in a Continuous Stirred Tank Reactor (CSTR). The feed enters at a volumetric flow rate v_0 = 100 L/min with an initial concentration C_A0 = 2.00 mol/L. If a conversion X_A = 0.80 (80%) is required, what reactor volume V is needed?

• A1,600 L
• B8,000 L
• C3,219 L
• D10,000 L

For an isothermal irreversible reaction with positive reaction order (n > 0) operating at identical volumetric feed rate and target conversion, why does an ideal Plug Flow Reactor (PFR) always require a smaller reactor volume than an ideal CSTR?

• ABecause the PFR operates at higher pressure due to hydraulic friction
• BBecause backmixing in a PFR accelerates molecular collisions near the walls
• CBecause reactant concentration decreases gradually along the PFR, maintaining a higher av…
• DBecause the CSTR has a larger heat exchange jacket that reduces its effective volume

A liquid-phase first-order irreversible decomposition reaction A -> Products (k = 0.100 min⁻¹) is to be carried out in an ideal Plug Flow Reactor (PFR). The volumetric flow rate is v_0 = 50.0 L/min. What reactor volume is required to achieve 90.0% conversion of reactant A (X_A = 0.90)?

• A4,500 L
• B500 L
• C450 L
• D1,151 L

In heterogeneous catalytic reaction engineering, what does an internal catalyst effectiveness factor eta < 1 indicate, and what occurs when the Thiele modulus (phi) is very large (phi >> 5)?

• AInternal pore diffusion resistance limits the reaction rate; for large phi, the reaction…
• BExternal mass transfer through the boundary film limits the reaction rate; for large phi,…
• CChemical surface kinetics is the sole rate-limiting step; for large phi, internal pore di…
• DThermodynamic equilibrium prevents further conversion; for large phi, the reaction become…

A continuous binary distillation column is designed using the McCabe-Thiele method. The reflux ratio is set to R = 2.50, and the distillate mole fraction is specified as x_D = 0.950. What is the slope and the y-intercept of the rectifying section operating line (ROL)?

• ASlope = 0.600, Intercept = 0.380
• BSlope = 0.714, Intercept = 0.271
• CSlope = 0.833, Intercept = 0.158
• DSlope = 0.286, Intercept = 0.714

A distillation feed stream enters a column as a two-phase mixture consisting of 60 mol% saturated liquid and 40 mol% saturated vapor. What is the value of the thermal condition parameter q, and what is the slope of the feed line (q-line) on the McCabe-Thiele diagram?

• Aq = 0.40, slope = +0.67
• Bq = 1.00, slope = vertical (infinite)
• Cq = 0.60, slope = -1.50
• Dq = 0.60, slope = +1.50

An equimolar binary feed (z_F = 0.500) is introduced as a saturated liquid (q = 1.00) into a continuous distillation column. The intersection of the vertical q-line with the vapor-liquid equilibrium curve occurs at x' = 0.500, y' = 0.700. If the desired distillate purity is x_D = 0.960, what is the minimum reflux ratio (R_min)?

• A0.565
• B0.769
• C2.30
• D1.30

In binary distillation design, what operational condition defines 'total reflux' (R -> infinity), and what does the Fenske equation compute under this condition?

• AAll overhead vapor is condensed and returned to the column as reflux with zero distillate…
• BZero reflux is returned to the column and all overhead vapor is withdrawn as product; the…
• CReflux ratio equals 1.0; the Fenske equation computes the optimal feed tray location
• DReboiler steam is completely shut off; the Fenske equation computes the flooding velocity

In a distillation column tray, the vapor entering from the tray below has a mole fraction y_(n+1) = 0.400. The vapor leaving tray n has y_n = 0.520. If the vapor in thermodynamic equilibrium with the liquid leaving tray n has a mole fraction y_n* = 0.600, what is the Murphree vapor tray efficiency (E_MV)?

• A52.0%
• B60.0%
• C86.7%
• D40.0%

At atmospheric pressure, an ethanol-water mixture forms a minimum-boiling homogeneous azeotrope at 78.15 °C with a composition of approximately 95.6 wt% (89.4 mol%) ethanol. Why can ordinary fractional distillation never produce pure anhydrous ethanol (>99.5 wt%) from a dilute aqueous fermentation broth, and what separation method is used industrially?

• AWater decomposes at 78 °C; industrial production uses vacuum freeze-drying
• BEthanol polymerizes into diethyl ether at high purity; industrial plants use reactive cry…
• CAt the azeotropic point, vapor and liquid compositions are identical (y = x, relative vol…
• DThe vapor pressure of water drops to zero at 78 °C; industry uses centrifugal sedimentati…

A dilute gas containing solute A is absorbed in a packed tower using pure solvent (x_in = 0). The absorption factor is A = L / (m·G) = 1.0, meaning the operating line and equilibrium line are straight and parallel. If the gas concentration must be reduced from y_in = 0.050 to y_out = 0.005, what is the required overall number of gas-phase transfer units (NTU_OG)?

• A4.5
• B1.0
• C2.30
• D9.0

A packed column is being sized to remove an environmental air pollutant via wet scrubbing. Mass transfer calculations determine that the process requires NTU_OG = 8.0 transfer units, and pilot plant testing with structured packing provides an overall height of a transfer unit HTU_OG = 0.75 m. What is the total height of the active packed bed (Z)?

• A6.00 m
• B10.67 m
• C8.75 m
• D0.094 m

In the hydrodynamic operation of countercurrent packed absorption and stripping towers, what physical condition defines 'flooding' (inundación), and what happens to the gas pressure drop per unit height of packing (Delta_P/Z) as the gas velocity approaches the flooding velocity?

• AThe liquid drains too rapidly through the packing; the pressure drop drops to zero
• BThe upward gas velocity exerts aerodynamic drag high enough to hold up liquid in the pack…
• CThe packing material dissolves completely into the solvent; the pressure drop fluctuates…
• DThe gas and liquid reach identical densities; the pressure drop remains strictly constant

An open aeration basin for industrial wastewater treatment operates at 25 °C and 1.00 atm total pressure. The Henry's law constant for dissolved oxygen in water at 25 °C is H = 4.38 × 10⁴ atm/mole fraction (where p_O2 = H·x_O2). If dry air contains 21.0 mol% O2, what is the equilibrium mole fraction of dissolved oxygen (x_O2) in the water?

• A2.28 × 10⁻⁵
• B9.20 × 10³
• C4.79 × 10⁻⁶
• D2.66 × 10⁻⁴

What is the primary thermodynamic and directional mass transfer difference between gas absorption (absorción) and stripping or desorption (desorción)?

• AAbsorption operates exclusively at temperatures above 500 °C, while stripping occurs at c…
• BAbsorption uses solid adsorbents, while stripping uses liquid-liquid extraction solvents
• CAbsorption always requires an irreversible chemical catalyst, while stripping is purely m…
• DIn absorption, solute is transferred from the gas phase into a liquid solvent (y > y*); i…

In a single-stage liquid-liquid extraction, 100 kg of an aqueous feed containing 8.00 wt% solute A (92.0 kg water carrier R) is contacted with 100 kg of pure organic solvent S. Water and solvent are mutually insoluble. The equilibrium distribution coefficient is K_D = Y_A / X_A = 0.800, where Y_A = kg solute / kg solvent and X_A = kg solute / kg water. What is the mass of solute A extracted into the organic phase?

• A3.72 kg
• B4.28 kg
• C6.40 kg
• D4.00 kg

On an equilateral triangular ternary phase diagram representing a liquid-liquid extraction system of Carrier (A), Solute (B), and Solvent (C) at constant temperature and pressure, what is the 'plait point' (punto de pliegue)?

• AThe point representing the maximum solubility of carrier in pure solvent
• BThe unique point on the binodal (miscibility) curve where tie lines converge to zero leng…
• CThe apex representing 100% pure solute B
• DThe center of gravity of the three-component feed mixture

Which combination of physical and chemical criteria represents the most desirable characteristics when selecting an extracting solvent for industrial liquid-liquid extraction?

• AIdentical boiling point to the solute, zero density difference with feed, and high mutual…
• BHigh chemical reactivity with the carrier, high toxicity, and high vapor pressure
• CHigh distribution coefficient (K_D), high selectivity (beta >> 1), significant density di…
• DLow distribution coefficient, equal viscosity to water, and tendency to form stable emuls…

In a multistage liquid-liquid extraction battery composed of mixer-settler units, what is the primary hydrodynamic function of the 'settler' (decantador)?

• ATo provide intense mechanical shear to create micro-droplets of solute
• BTo evaporate the volatile solvent by indirect steam heating
• CTo strip residual dissolved gases under deep vacuum
• DTo provide sufficient quiescent residence time for droplets in the dispersed liquid emuls…

Why is multistage countercurrent extraction operationally superior to multistage cross-current extraction for large-scale industrial chemical recovery?

• ACountercurrent flow achieves a higher solute recovery using significantly less total solv…
• BCountercurrent extraction operates without any pumps or motors, relying solely on capilla…
• CCross-current extraction requires zero solvent recovery because solvent is permanently co…
• DCountercurrent flow eliminates the requirement for phase density differences

During the batch convective drying of a wet granular solid under constant drying conditions (constant air temperature, humidity, and velocity), how does the drying rate (N, kg moisture/m²·h) evolve as the moisture content X (kg moisture/kg dry solid) decreases?

• AThe drying rate starts at zero and increases linearly until the solid is completely dry
• BThe drying rate remains constant (constant-rate period) from initial moisture down to the…
• CThe drying rate decreases exponentially from the very beginning with no constant period
• DThe drying rate is completely independent of moisture content and remains constant down t…

A batch tray dryer dries a porous wet solid cake with an exposed surface area A = 2.00 m² and dry solid mass M_s = 50.0 kg. The constant drying rate under prevailing conditions is N_c = 1.25 kg moisture/m²·h. If the moisture content is reduced from an initial X1 = 0.350 kg water/kg dry solid to the critical moisture content X_c = 0.150 kg water/kg dry solid, what is the drying time required for this constant-rate period?

• A2.00 h
• B8.00 h
• C4.00 h
• D1.25 h