100+ Free Registered Chemical Engineer Practice Questions

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The China Registered Chemical Engineer examination is the mandatory national licensing credential for process and chemical design engineers in China. This 100-question English-language adaptation covers chemical thermodynamics (EOS, VLE, fugacity), fluid mechanics & heat exchanger design, separation processes (McCabe-Thiele distillation, Kremser absorption), reactor design (CSTR/PFR/catalysis), and petrochemical safety codes (GB 50160, PSV sizing, HAZOP).

Sample Registered Chemical Engineer Practice Questions

Try these sample questions to test your Registered Chemical Engineer exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In the Van der Waals equation of state $(P + a/V_m^2)(V_m - b) = RT$, what physical phenomena do the parameters $a$ and $b$ specifically account for?

A.Parameter $a$ accounts for attractive intermolecular forces between fluid molecules, while $b$ accounts for the finite volume occupied by the molecules (co-volume).

B.Parameter $a$ accounts for molecular repulsive forces at high velocity, while $b$ accounts for association and hydrogen bonding.

C.Parameter $a$ accounts for the finite volume occupied by molecules, while $b$ accounts for attractive intermolecular forces.

D.Parameter $a$ accounts for deviation from ideal temperature, while $b$ accounts for pressure-dependent gas compressibility.

Explanation: In the Van der Waals equation of state, the parameter $a$ represents the attractive intermolecular forces that reduce the effective pressure exerted on the container walls ($a/V_m^2$), while $b$ represents the excluded volume or co-volume occupied by one mole of molecules ($V_m - b$). At the critical point, these parameters relate to critical properties via $a = 27 R^2 T_c^2 / (64 P_c)$ and $b = R T_c / (8 P_c)$.

2A pure hydrocarbon gas at $T = 350\text{ K}$ and $P = 2.0\text{ MPa}$ has a second virial coefficient $B = -180\text{ cm}^3/\text{mol}$. Using the truncated virial equation $Z = 1 + \frac{B P}{R T}$, what is the compressibility factor $Z$ of the gas? (Universal gas constant $R = 8.314\text{ J/(mol}\cdot\text{K)} = 8.314\text{ MPa}\cdot\text{cm}^3/(\text{mol}\cdot\text{K})$)

A.0.952

B.0.876

C.1.048

D.0.760

Explanation: Using the truncated pressure-explicit virial equation of state $Z = 1 + \frac{B P}{R T}$: substitute $B = -180\text{ cm}^3/\text{mol}$, $P = 2.0\text{ MPa}$, and $R T = 8.314 \times 350 = 2909.9\text{ MPa}\cdot\text{cm}^3/\text{mol}$. Then $\frac{B P}{R T} = \frac{-180 \times 2.0}{2909.9} = -0.1237$. Therefore, $Z = 1 - 0.1237 = 0.8763 \approx 0.876$.

3In the Soave-Redlich-Kwong (SRK) cubic equation of state $P = \frac{R T}{V_m - b} - \frac{a(T)}{V_m (V_m + b)}$, how does the temperature-dependent attraction parameter $a(T)$ incorporate the acentric factor $\omega$?

A.$a(T) = a_c \alpha(T_r, \omega)$, where $\alpha^{0.5} = 1 + m(1 - T_r^{0.5})$ and $m = 0.480 + 1.574\omega - 0.176\omega^2$

B.$a(T) = a_c / T_r^{0.5}$, where acentricity is neglected for non-polar hydrocarbons

C.$a(T) = a_c [1 + \omega (1 - T_r)]^2$, where $m$ is directly proportional to critical compressibility $Z_c$

D.$a(T) = a_c \exp(-\omega T_r)$, where $\alpha$ decays exponentially with reduced temperature

Explanation: Soave modified the Redlich-Kwong equation by replacing the $a / \sqrt{T}$ term with $a(T) = a_c \alpha(T_r, \omega)$, where $\alpha^{0.5} = 1 + m(1 - \sqrt{T_r})$ and $m = 0.480 + 1.574\omega - 0.176\omega^2$. This modification significantly improved vapor pressure and phase equilibrium predictions for non-spherical and polyatomic hydrocarbon molecules.

4Which of the following expressions represents the Peng-Robinson (PR) equation of state and its theoretical critical compressibility factor $Z_c$?

A.$P = \frac{R T}{V_m - b} - \frac{a(T)}{V_m(V_m + b)}$ with a universal critical compressibility $Z_c = 0.3333$

B.$P = \frac{R T}{V_m - b} - \frac{a(T)}{V_m(V_m + b) + b(V_m - b)}$ with a universal critical compressibility $Z_c = 0.3074$

C.$P = \frac{R T}{V_m - b} - \frac{a}{V_m^2}$ with a universal critical compressibility $Z_c = 0.3750$

D.$P = \frac{R T}{V_m - b} - \frac{a(T)}{V_m^2 + 2b V_m - b^2}$ with a universal critical compressibility $Z_c = 0.2800$

Explanation: The Peng-Robinson equation of state (1976) is written as $P = \frac{R T}{V_m - b} - \frac{a(T)}{V_m^2 + 2 b V_m - b^2} = \frac{R T}{V_m - b} - \frac{a(T)}{V_m(V_m + b) + b(V_m - b)}$. It yields a theoretical critical compressibility factor $Z_c = 0.3074$, which provides more accurate liquid density predictions than the SRK equation ($Z_c = 0.3333$) or Van der Waals ($Z_c = 0.375$).

5What is the thermodynamic definition of the fugacity coefficient $\phi_i$ of a pure component $i$ at temperature $T$ and pressure $P$?

A.$\ln \phi_i = \int_0^P \left( \frac{V_m}{RT} - \frac{1}{P} \right) dP = \int_0^P \frac{Z - 1}{P} dP$

B.$\ln \phi_i = \int_0^P \left( \frac{RT}{V_m} - P \right) dP$

C.$\phi_i = \exp\left( \frac{P V_m}{RT} \right)$

D.$\phi_i = \frac{P}{P_i^{\text{sat}}} \exp\left( \frac{V_L (P - P_i^{\text{sat}})}{RT} \right)$

Explanation: From the fundamental property relation $d G_i = V_m dP - S_m dT$ at constant temperature, the residual Gibbs free energy is $G_i^R = RT \ln \phi_i = \int_0^P (V_m - V_m^{\text{ideal}}) dP = \int_0^P \left( V_m - \frac{RT}{P} \right) dP$. Dividing by $RT$ gives $\ln \phi_i = \int_0^P \frac{Z - 1}{P} dP$.

6The residual enthalpy $H^R = H - H^{\text{ideal}}$ of a real gas at temperature $T$ and pressure $P$ can be derived from $P-V-T$ data and Maxwell relations as which of the following integrals?

A.$H^R = \int_0^P \left[ T \left( \frac{\partial P}{\partial T} \right)_{V_m} - P \right] dP$

B.$H^R = \int_0^P \left[ V_m - T \left( \frac{\partial V_m}{\partial T} \right)_P \right] dP$

C.$H^R = \int_0^T C_p dT - P V_m$

D.$H^R = -R T^2 \int_0^P \left( \frac{\partial Z}{\partial P} \right)_T dP$

Explanation: Using the fundamental thermodynamic differential $d H = T dS + V dP$ and the Maxwell relation $(\partial S / \partial P)_T = -(\partial V / \partial T)_P$, we obtain $(d H / dP)_T = V - T (\partial V / \partial T)_P$. For an ideal gas, $V^{\text{ideal}} - T (\partial V^{\text{ideal}} / \partial T)_P = 0$. Integrating the difference from $0$ to $P$ yields $H^R = \int_0^P [V_m - T (\partial V_m / \partial T)_P] dP$.

7According to the Lewis-Randall rule for ideal solutions, the fugacity of species $i$ in a gas or liquid mixture, $\hat{f}_i$, is related to its pure-component fugacity $f_i$ by which expression?

A.$\hat{f}_i = y_i P$

B.$\hat{f}_i = \gamma_i y_i f_i$

C.$\hat{f}_i = x_i f_i$

D.$\hat{f}_i = x_i H_i$

Explanation: The Lewis-Randall rule states that in an ideal solution, the fugacity of component $i$ in the mixture is directly proportional to its mole fraction multiplied by the fugacity of pure component $i$ at the same temperature and total system pressure: $\hat{f}_i = x_i f_i$ (or $y_i f_i$).

8A binary liquid mixture follows the one-parameter Margules excess Gibbs energy model $\frac{G^E}{RT} = A x_1 x_2$ with $A = 1.20$. At equimolar composition ($x_1 = x_2 = 0.50$), what are the activity coefficients $\gamma_1$ and $\gamma_2$ of the two components?

A.$\gamma_1 = \gamma_2 = 1.350$

B.$\gamma_1 = \gamma_2 = 1.822$

C.$\gamma_1 = \gamma_2 = 1.150$

D.$\gamma_1 = \gamma_2 = 3.320$

Explanation: For the symmetric one-parameter Margules model, $\ln \gamma_1 = A x_2^2$ and $\ln \gamma_2 = A x_1^2$. At $x_1 = x_2 = 0.50$, $\ln \gamma_1 = 1.20 \times (0.50)^2 = 1.20 \times 0.25 = 0.30$. Therefore, $\gamma_1 = \gamma_2 = \exp(0.30) = 1.34986 \approx 1.350$.

9Which of the following is a key theoretical characteristic and known limitation of the Wilson activity coefficient model for liquid mixtures?

A.It incorporates local composition concepts to accurately model highly non-ideal miscible systems, but it cannot predict liquid-liquid phase splitting (LLE).

B.It is capable of predicting both vapor-liquid and liquid-liquid equilibria with equal accuracy across all temperature ranges.

C.It assumes random molecular mixing and neglects differences in molecular size and intermolecular interaction energy.

D.It can only be applied to symmetric binary systems where $\Lambda_{12} = \Lambda_{21}$.

Explanation: The Wilson model (1964) introduced the concept of local composition to account for differences in molecular size and interaction energies, successfully describing strongly non-ideal vapor-liquid equilibrium (VLE). However, due to its mathematical formulation with positive second derivatives of $G^E$, the Wilson equation cannot yield two liquid phases and is inherently incapable of modeling liquid-liquid equilibrium (LLE).

10In the NRTL (Non-Random Two-Liquid) equation, what is the physical meaning of the non-randomness parameter $\alpha_{12}$?

A.It represents the ratio of the molar volumes of component 1 to component 2 in the pure liquid state.

B.It characterizes the tendency of the mixture to form non-random local molecular structures around central molecules, typically varying between 0.20 and 0.47.

C.It denotes the critical temperature ratio $T_{c1} / T_{c2}$ used to scale the energy interaction parameters.

D.It is a binary interaction parameter that must equal 1.0 for all partially miscible liquid mixtures.

Explanation: In Renon and Prausnitz's NRTL model, $\alpha_{12}$ is the non-randomness parameter related to the ordering and local structure in the solution. When $\alpha_{12} = 0$, the mixture is completely random (like the two-suffix Margules / regular solution model). For typical hydrocarbon-alcohol or organic systems, $\alpha_{12}$ is set between 0.20 and 0.47 (often 0.30).

About the Registered Chemical Engineer Exam

The Registered Chemical Engineer Qualification Examination (全国注册化工工程师执业资格考试) is a national survey-and-design registered-engineer qualification administered under MOHURD and MOHRSS. The syllabus spans chemical thermodynamics, transport and heat transfer, separation, reaction engineering, process design, and safety. This bank is an English-language MCQ study adaptation, not an official translation or format simulation and not a substitute for the professional case paper.

Assessment

Foundation Exam: Public Basic (120 pts, 4.0 hrs) + Specialty Basic (120 pts, 4.0 hrs); Professional Exam: Professional Knowledge (200 pts, 6.0 hrs total across morning/afternoon) + Professional Case Analysis (100 pts, 6.0 hrs total across morning/afternoon).

Time Limit

3.0 - 4.0 hours per paper session

Passing Score

60%

Exam Fee

Set by the provincial examination authority; consult the current registration notice (Ministry of Housing and Urban-Rural Development (MOHURD, 住房和城乡建设部) and Ministry of Human Resources and Social Security (MOHRSS, 人力资源和社会保障部))

Registered Chemical Engineer Exam Content Outline

20%

chemical-engineering-thermodynamics

Thermodynamic properties of pure fluids and fluid mixtures: PVT equations of state (Van der Waals, Redlich-Kwong, Soave-Redlich-Kwong SRK, Peng-Robinson PR), compressibility factor Z, fugacity and fugacity coefficients (phi_i), activity coefficient models (Margules, Van Laar, Wilson, NRTL, UNIQUAC, UNIFAC), vapor-liquid equilibrium (VLE) calculations (bubble point, dew point, flash distillation, relative volatility, azeotropic systems), liquid-liquid equilibrium (LLE), chemical reaction equilibrium (equilibrium constant K_a, standard Gibbs free energy change Delta G° = -RT ln K, temperature dependence via Van 't Hoff equation), residual enthalpy and entropy, and refrigeration/liquefaction thermodynamic cycles.

25%

fluid-flow-and-heat-transfer

Fluid mechanics and heat transfer in chemical processing equipment: Navier-Stokes momentum equations, continuity equation, extended Bernoulli equation with mechanical work and friction loss, laminar vs turbulent flow regimes (Reynolds number Re), Darcy-Weisbach friction factor, Moody diagram, pipe network pressure drop and equivalent length of fittings, pump performance curves, system resistance curves, Net Positive Suction Head (NPSH_a vs NPSH_r) and cavitation, conductive heat transfer (Fourier's law, composite walls, critical insulation radius), convective heat transfer (dimensionless correlations Nu, Re, Pr, Gr), shell-and-tube heat exchanger design per GB/T 151 (LMTD, correction factor F_T, overall heat transfer coefficient U, fouling resistance), radiation heat exchange (Stefan-Boltzmann law, view factors, emissivity), and phase change heat transfer (nucleate boiling, critical heat flux CHF, Nusselt vertical film condensation).

25%

mass-transfer-and-separation-processes

Principles and equipment sizing for mass transfer unit operations: Fick's first and second laws of diffusion, equimolar counterdiffusion vs diffusion through stagnant film, two-film mass transfer theory and overall mass transfer coefficients (K_y, K_x), binary distillation column design using the McCabe-Thiele method (operating lines, q-line feed thermal condition, minimum reflux ratio R_min, theoretical tray count N), multicomponent fractionation (Fenske equation for N_min, Underwood equations for R_min, Gilliland correlation), tray hydraulic sizing (weeping, entrainment, flooding, pressure drop), Murphree tray efficiency, gas absorption and desorption in packed towers (Henry's law, operating line, Kremser-Brown-Souders equation, Height of a Transfer Unit HTU, Number of Transfer Units NTU, HETP), liquid-liquid extraction (ternary phase equilibria, triangular coordinates, single/multistage countercurrent extraction), industrial drying operations (psychrometric chart, wet-bulb/dew-point temperatures, drying rate curves, constant/falling rate periods), and membrane separations (reverse osmosis, gas permeation).

15%

chemical-reaction-engineering

Kinetics of homogeneous and heterogeneous chemical reactions and industrial reactor design: Reaction rate expressions, reaction order, Arrhenius temperature dependency (k = A exp(-E_a / RT)), activation energy calculation, ideal reactor performance equations for isothermal and non-isothermal operation (Batch reactor, Continuous Stirred-Tank Reactor CSTR, Plug Flow Reactor PFR), space time (tau) and space velocity (LHSV, WHSV), multiple reaction networks (parallel and series reactions, instantaneous yield, overall selectivity optimization), autothermal operation and reactor thermal stability/runaway criteria, heterogeneous gas-solid catalysis (adsorption isotherms Langmuir-Hinshelwood, internal pore diffusion, Thiele modulus phi, catalyst effectiveness factor eta, Weisz-Prater criterion), and non-ideal flow characterization using Residence Time Distribution (RTD, pulse/step tracer response, E(t) and F(t) functions, mean residence time, variance, tanks-in-series and axial dispersion models).

15%

process-design-safety-and-plant-engineering

Process engineering documents, plant layout, process safety, and environmental protection in accordance with Chinese national codes and industry standards: Process Flow Diagrams (PFD) and Piping & Instrumentation Diagrams (P&ID) symbology per HG/T 20559, safety relief valve (PSV/SRV) and rupture disc relief capacity and orifice sizing per API 520 / GB/T 150 / HG/T 20570, Petrochemical Plant Fire Protection Standard GB 50160 (equipment spacing, fire separation distances, fire dikes for flammable liquid storage tanks), hazardous area electrical classification per GB 50058 (Zone 0, Zone 1, Zone 2), Process Safety Management and Hazard and Operability (HAZOP) analysis, Layer of Protection Analysis (LOPA), Safety Integrity Level (SIL) allocation per GB/T 21109 / IEC 61511, flammability limits (LFL/UFL, Le Chatelier's rule for gas mixtures), flash point classification of flammable liquids (Class甲/乙/丙 per GB 50160), basic process control loops (feedback, cascade, feedforward, ratio, override control), atmospheric emission abatement (VOCs recovery, SCR/SNCR desulfurization/denitrification), wastewater treatment, and chemical equipment materials selection and corrosion control (austenitic stainless steels, stress corrosion cracking SCC).

How to Pass the Registered Chemical Engineer Exam

What You Need to Know

Passing score: 60%
Assessment: Foundation Exam: Public Basic (120 pts, 4.0 hrs) + Specialty Basic (120 pts, 4.0 hrs); Professional Exam: Professional Knowledge (200 pts, 6.0 hrs total across morning/afternoon) + Professional Case Analysis (100 pts, 6.0 hrs total across morning/afternoon).
Time limit: 3.0 - 4.0 hours per paper session
Exam fee: Set by the provincial examination authority; consult the current registration notice

Keys to Passing

Work through all 100 available questions
Review every answer and explanation
Track weak areas and revisit them
Use our AI tutor for tough concepts

Registered Chemical Engineer Study Tips from Top Performers

1Master Thermodynamic Equations of State: Practice solving compressibility factors and vapor-liquid equilibria using Van der Waals, SRK, and Peng-Robinson equations of state, and calculate activity coefficients using Margules and Wilson equations.

2Internalize Transport & Unit Operations Calculations: Practice calculating friction head loss (Darcy-Weisbach), pump NPSH margins, shell-and-tube heat exchanger area (Q = U A Delta T_lm F_T), and distillation stage counts using both McCabe-Thiele graphical and Fenske analytical methods.

3Drill Chemical Reactor Performance Equations: Solve isothermal and adiabatic conversion balances for batch, CSTR, and PFR systems, evaluate reaction kinetics using Arrhenius equations, and calculate the Thiele modulus and catalyst effectiveness factor.

4Memorize Petrochemical Safety Code Provisions: Thoroughly review GB 50160 fire separation distances, storage tank dike volumetric capacities (100% of largest tank or 50% of total group volume), Class 甲/乙/丙 liquid flash point thresholds, and GB 50058 Zone 0/1/2 definitions.

5Calculate Safety Relief Valve Sizing Accurately: Practice determining required discharge capacity and minimum relief orifice area for vapor and liquid overpressure scenarios per API 520 / GB/T 150 / HG/T 20570.

Frequently Asked Questions

What is the China Registered Chemical Engineer Qualification Examination?

The Registered Chemical Engineer (注册化工工程师) qualification examination is the official national statutory licensing examination administered jointly by the Ministry of Housing and Urban-Rural Development (MOHURD, 住房和城乡建设部) and the Ministry of Human Resources and Social Security (MOHRSS, 人力资源和社会保障部). It certifies that an engineer possesses the advanced technical expertise, safety knowledge, and engineering capability required to lead chemical process designs, approve equipment specifications, and sign statutory engineering documents.

What is the examination structure, passing threshold, and testing sequence?

The examination is divided into two distinct stages: (1) Foundation Examination (基础考试), which includes Public Basic (120 pts, 4 hrs) and Specialty Basic (120 pts, 4 hrs), requiring a passing score of 132/240 points in a single year; and (2) Professional Examination (专业考试), which includes Professional Knowledge (200 pts, 6 hrs) and Professional Case Analysis (100 pts, 6 hrs). Candidates must pass both professional papers in the same examination year with at least 60% (120/200 and 60/100 points, respectively) after meeting the requisite engineering practice prerequisites.

What core subjects and calculation methods are tested on the examination?

The exam rigorously tests chemical thermodynamics (cubic equations of state, fugacity, activity coefficients, VLE flash), fluid flow and pump NPSH calculations, heat exchanger LMTD/NTU sizing, McCabe-Thiele and Fenske-Underwood distillation, Kremser absorption, ideal chemical reactor sizing (CSTR/PFR), catalyst effectiveness factors, PSV relief area sizing, and plant layout spacing per GB 50160.

What national codes and engineering design standards are essential for the professional exam?

Key standards include GB 50160 (Petrochemical Plant Design Fire Protection Standard), GB 50016 (Code for Fire Protection Design of Buildings), GB 50058 (Code for Design of Electrical Installations in Hazardous Areas), GB/T 150 (Pressure Vessels), GB/T 151 (Heat Exchangers), HG/T 20559 (P&ID Drafting Standards), and HG/T 20570 (Process Equipment Sizing).

What are the eligibility requirements for the Foundation and Professional examinations?

Graduates with a bachelor's degree in Chemical Engineering and Technology can sit for the Foundation Examination upon graduation. To sit for the Professional Examination, candidates who passed the Foundation Exam must accumulate 3 to 5 years of verified professional chemical engineering design experience depending on whether their degree program is nationally accredited.

Why is this practice question bank presented in English?

This is an English-language MCQ study adaptation, not an official translation or format simulation and not a substitute for professional case work. Official Chinese terms, formulas, and standard identifiers integral to the syllabus are retained for cross-reference.