PE Chemical

A distillation column separates a feed containing 40 mol% ethanol and 60 mol% water into a distillate product containing 85 mol% ethanol and a bottoms product containing 5 mol% ethanol. If the feed rate is 1000 mol/h, what is the flow rate of the distillate product?

• A353 mol/h
• B412 mol/h
• C438 mol/h
• D467 mol/h

What is the primary purpose of performing a degree-of-freedom analysis before solving material balance problems?

• ATo determine the molecular weight of each component
• BTo determine if the problem is properly specified and solvable
• CTo calculate the heat of reaction
• DTo determine the reaction rate constant

100 kmol/h of methane is burned with 50% excess air in a furnace. Assuming complete combustion, what is the molar flow rate of unreacted (excess) O₂ in the flue gas?

• A50 kmol/h
• B100 kmol/h
• C200 kmol/h
• D300 kmol/h

An evaporator concentrates a 10 wt% NaCl solution to 35 wt%. If the feed rate is 5000 kg/h, what is the rate of water evaporated?

• A2860 kg/h
• B3214 kg/h
• C3571 kg/h
• D4000 kg/h

Fresh feed of 100 mol/h of pure A enters a reactor that achieves 60% single-pass conversion of A. The unreacted A is perfectly separated and 50% of it is recycled to the reactor inlet (the rest is purged). The overall conversion of A in the process is:

• A60%
• B70%
• C75%
• D90%

For an adiabatic reactor operating at steady state, which statement about the energy balance is correct?

• AThe heat transfer rate equals the change in kinetic energy
• BThe enthalpy of the outlet stream equals the enthalpy of the inlet stream
• CThe sum of enthalpy changes of all streams equals the heat of reaction
• DThe potential energy change equals the shaft work

What is the limiting reactant in the combustion of a gas mixture containing 30 mol% CO, 20 mol% H2, and 50 mol% N2 when burned with 40% excess air?

• ACO
• BH2
• CO2
• DN2

A tank initially contains 500 kg of water. A salt solution containing 20 wt% salt enters at 100 kg/h, and the well-mixed contents leave at the same rate. What is the mass of salt in the tank after 5 hours?

• A63.2 kg
• B71.8 kg
• C82.5 kg
• D95.4 kg

In a bypass stream configuration, 30% of the feed bypasses a reactor and the remaining 70% goes through the reactor where 60% conversion is achieved. What is the overall conversion for the combined stream?

• A30%
• B42%
• C52%
• D60%

Which of the following is TRUE about the extent of reaction (ξ)?

• AIt has units of time
• BIt is always positive for all species in a reaction
• CIt is the same for all species participating in a single reaction
• DIt equals the fractional conversion for the limiting reactant

The higher heating value (HHV) of a fuel differs from the lower heating value (LHV) by:

• AThe heat of vaporization of water in the combustion products
• BThe heat capacity of the fuel
• CThe activation energy of combustion
• DThe sensible heat of the exhaust gases

In a steady-state system with two input streams and one output stream, if the total mass flow rate of input 1 is 50 kg/h and input 2 is 75 kg/h, what is the mass flow rate of the output stream?

• A50 kg/h
• B75 kg/h
• C100 kg/h
• D125 kg/h

A dryer processes wet solids containing 40% water (wet basis) to produce solids containing 5% water. If 1000 kg/h of wet solids enter, what mass of water is removed?

• A342 kg/h
• B368 kg/h
• C395 kg/h
• D421 kg/h

The theoretical air required for complete combustion is best defined as:

• AThe minimum air needed to achieve the highest possible temperature
• BThe air required to convert all fuel carbon to CO and hydrogen to H2O
• CThe air required to convert all fuel carbon to CO2 and hydrogen to H2O
• DThe air required to minimize NOx formation

In an energy balance for a reactive system, the standard heat of reaction is typically evaluated at:

• AThe reactor inlet temperature
• BThe reactor outlet temperature
• C298 K (25°C)
• DThe average of inlet and outlet temperatures

A heat exchanger cools 500 kg/h of oil (Cp = 2.0 kJ/kg·K) from 150°C to 50°C by heating water (Cp = 4.18 kJ/kg·K) from 20°C to 60°C. What is the required water flow rate?

• A478 kg/h
• B512 kg/h
• C598 kg/h
• D645 kg/h

What is the dew point of a gas mixture containing 10 mol% water vapor at 1 atm total pressure?

• AThe temperature where water first begins to condense when cooled
• BThe temperature where all water vapor condenses
• CThe temperature where the vapor pressure equals total pressure
• DThe critical temperature of water

A purge stream is typically used in processes with recycle to:

• ARemove accumulated inerts or byproducts
• BIncrease the overall conversion of reactants
• CReduce the reactor volume required
• DIncrease the selectivity of the desired product

For the reaction 2A + B → C, if 100 mol of A and 50 mol of B are fed, and the reaction goes to completion, how many moles of C are produced?

• A25 mol
• B50 mol
• C75 mol
• D100 mol

In an unsteady-state batch reactor, the energy accumulation term accounts for:

• AOnly the change in kinetic energy of the fluid
• BThe change in internal energy of the system contents
• CThe heat transfer across the reactor walls only
• DThe shaft work done by agitators

According to the first law of thermodynamics for a closed system, which equation is correct?

• AΔU = Q - W
• BΔU = Q + W
• CΔH = Q + W
• DΔS = Q/T

For an isentropic process of an ideal gas, which relationship is correct?

• ATV^(γ-1) = constant
• BPV = constant
• CTV^γ = constant
• DP^γ V = constant

The compressibility factor Z for a real gas is defined as:

• AZ = PV/RT
• BZ = RT/PV
• CZ = P/ρRT
• DZ = (P + a/V^2)(V - b)/RT

What is the maximum work obtainable from a heat engine operating between reservoirs at 800 K and 300 K?

• A37.5% of heat input
• B50% of heat input
• C62.5% of heat input
• D75% of heat input

The van der Waals equation of state modifies the ideal gas law by accounting for:

• AOnly intermolecular attractive forces
• BOnly the finite volume of molecules
• CBoth molecular volume and intermolecular forces
• DQuantum mechanical effects

For a pure component, the chemical potential μ equals:

• AThe internal energy
• BThe enthalpy
• CThe Gibbs free energy per mole
• DThe Helmholtz free energy

At vapor-liquid equilibrium for a binary mixture, which condition must be satisfied?

• AThe total pressure equals the sum of pure component vapor pressures
• BThe chemical potential of each component is equal in both phases
• CThe temperature of the vapor is higher than the liquid
• DThe mole fractions in both phases are equal

The equilibrium constant K for a gas-phase reaction depends on:

• APressure only
• BTemperature only
• CBoth temperature and pressure
• DNeither temperature nor pressure

For an exothermic reaction, increasing the temperature will:

• AIncrease the equilibrium constant
• BDecrease the equilibrium constant
• CNot affect the equilibrium constant
• DAlways increase the reaction rate

The fugacity coefficient φ for a pure gas approaches what value as pressure approaches zero?

• A0
• B0.5
• C1
• DInfinity

For a binary azeotrope, which statement is true at the azeotropic composition?

• AThe vapor and liquid compositions are equal
• BThe mixture behaves as an ideal solution
• CThe bubble point temperature equals the dew point temperature
• DBoth A and C

The second law of thermodynamics states that for any spontaneous process:

• AThe total energy of the universe is constant
• BThe entropy of the universe increases
• CThe enthalpy of the system decreases
• DThe Gibbs free energy of the universe increases

In the equation dG = VdP - SdT, the natural variables of Gibbs free energy are:

• AVolume and temperature
• BPressure and temperature
• CEntropy and volume
• DInternal energy and volume

For a closed system undergoing an irreversible process from state 1 to state 2, which inequality holds?

• AΔS_system < ∫(δQ/T)
• BΔS_system > ∫(δQ/T)
• CΔS_system = ∫(δQ/T)
• DΔS_universe < 0