What do FE Chemical practice problems actually look like?

Mostly multiple choice with four options, usually phrased 'most nearly', and the options sit close enough that you cannot eliminate them by inspection. In the diffusion problem below, the right answer and the result of the handbook's formula for a different situation are 14% apart. Many carry a figure: a process flow sketch, a stress element, a concentration profile, a sieve curve. NCEES gives 110 questions in a 6-hour appointment, of which 5 hours 20 minutes is exam time, so the working time per question is under three minutes once you allow for reading, a handbook lookup and a check. NCEES also uses alternative item types (multiple correct answers, point-and-click, drag-and-drop and fill-in-the-blank), each scored right or wrong with no partial credit.

What is on the FE Chemical exam that is not on any other FE exam?

Four knowledge areas: Mass Transfer and Separation at 8-12 questions, Chemical Reaction Engineering at 7-11, Process Design at 7-11, and Solids Handling at 3-5. None of the five other FE specifications has an area for any of them. Process Design and Solids Handling appear nowhere else at all; FE Environmental does list reactors, kinetics and a few separation processes (adsorption, membranes, air stripping) as subtopics. Together the four areas carry 25 to 35 of the 110 questions; their maxima add to 39, but the other 13 areas' minimums already take 75. Material/Energy Balances, the largest area here, is not in that list: FE Environmental lists mass and energy balances under three of its own areas.

How many questions are on each FE Chemical topic?

Material/Energy Balances is the largest at 10-15. Fluid Mechanics/Dynamics, Thermodynamics, Heat Transfer, and Mass Transfer and Separation follow at 8-12 each; Chemistry and Biology, Chemical Reaction Engineering, and Process Design at 7-11 each; Mathematics 6-9; Safety, Health and Environment 5-8; Probability and Statistics, Engineering Sciences, Materials Science, Economics and Process Control 4-6 each; Solids Handling and Ethics and Professional Practice 3-5 each. That is 17 knowledge areas, more than FE Civil, Mechanical or Other Disciplines carry, and the ranges sum to between 100 and 153 against an exam of 110.

Is FE Chemical harder than the other FE exams?

Different rather than harder, and the difference is specialization rather than difficulty. No single area dominates: the largest, Material/Energy Balances at 10-15 questions, is the same size as the largest areas on FE Civil and FE Mechanical. But roughly a quarter to a third of the questions come from subjects most candidates meet only on a chemical engineering degree. Whether that makes it harder depends entirely on what you studied.

What reference material do you get on the FE Chemical exam?

The exam is closed book with an electronic reference: the NCEES FE Reference Handbook is supplied on-screen as a searchable PDF, and no personal copies or outside material are allowed. Practice with the searchable PDF rather than a printed copy. With 17 knowledge areas to move between, finding the right page quickly is a substantial part of the skill being tested.

FE Chemical practice problems: the specialist FE exam

Four knowledge areas on this exam appear on no other FE exam: mass transfer and separation, chemical reaction engineering, process design, and solids handling. Between them they are 25 to 35 of the 110 questions. Here are three practice problems, worked in full, including one where the handbook prints the formula for the wrong situation one page before the right one.

Updated October 6, 2026 · by the FE → PE Prep team

110

Questions

5h 20m

Exam time

Knowledge areas

25–35

ChemE-only questions

The arithmetic is easy. The bookkeeping is not.

Each of the three problems below is a two-line calculation. None of them needs calculus or an iteration. The handbook prints the diffusion and overshoot formulas, and the evaporator needs only mass in = mass out. They are still hard, and they are hard in a way that practicing more algebra will not fix.

Some of the wrong answers are real quantities or real formulas. In the overshoot question, one distractor is the decay ratio, a genuine number from the same response. In the diffusion question, one is the handbook's own formula for a different situation. Nothing about writing either down feels like an error.
The difficulty is deciding what to compute, not how. Diffusion has two handbook models, and the stem tells you which one applies; a mass balance asks for one stream out of three. Getting those right is comprehension, and comprehension is what a three-minute clock attacks.
One term copied in the wrong place gives a wrong answer that looks just as reasonable. In the overshoot problem below, moving a square root from the denominator to the numerator turns 16.3% into 25.7%. There is no order-of-magnitude glance that saves you, and both numbers are on the page.
Seventeen knowledge areas means seventeen places in the handbook. That is more than FE Civil, FE Mechanical or FE Other Disciplines carry, and searching well is a bigger share of the skill here than on any depth-heavy exam.

Three practice problems

One from Material and Energy Balances, the largest area on the exam; one from Mass Transfer, which no other FE exam has as a knowledge area; and one from Process Control. All three are drawn from our free FE Chemical set. Try each before opening the solution, and read the distractor notes.

1. Evaporation rate from a mass balance

Material and Energy Balances is the largest area on this exam at 10–15 questions, and this is its archetype. Two balances, one subtraction, no calculus. The whole difficulty is keeping track of where the water goes.

1
medium
A. Steady-state material balances
A single-effect evaporator concentrates 1000 kg/h of an aqueous sugar solution containing 12 wt% sugar to a product of 30 wt% sugar. The vapor leaving the evaporator is pure water. At steady state, the rate at which water is evaporated is most nearly:
Figure — drag or pinch to move around
1. 180 kg/h
2. 600 kg/h
3. 760 kg/h
4. 880 kg/h
Show the answer & worked solution
Answer: B.600 kg/h
Steady state with no reaction: mass in = mass out, for the total and for the solute (sugar), which leaves only in the concentrate $L$ (the same balances the FE Handbook prints for a flash drum, p. 250). Solute: $F w_F = L w_L$ , so $L = 1000(0.12)/0.3 = 400$ kg/h. Total: $V = F - L = 1000 - 400 = 600$ kg/h. Check on the water: $880 = 600 + 400(0.7)$ . Distractors: the water in the concentrate figured on the FEED rate, $F(1-w_L)$ , instead of on $L$ , giving $F(w_L - w_F) = 180$ kg/h; the water leaving in the concentrate written as $L w_L$ (its sugar fraction) instead of $L(1-w_L)$ , $880 - 120 = 760$ kg/h; and ALL the water in the feed taken as evaporated, $F(1-w_F) = 880$ kg/h (the water that leaves with the concentrate forgotten).

What the distractors teach

The sugar leaves only in the product, so the solute balance fixes the concentrate: 1000 × 0.12 / 0.30 = 400 kg/h, and the other 600 kg/h leaves as vapor. Every wrong answer is a water balance done carelessly. 880 kg/h assumes all the water in the feed boils off, forgetting the water that leaves with the product. 760 kg/h writes the water in the concentrate as 400 × 0.30, its sugar fraction, instead of 400 × 0.70. 180 kg/h figures the concentrate's water on the 1000 kg/h feed instead of on the 400 kg/h that actually leaves. Write the solute balance first and the water takes care of itself.

2. Steady molar flux across a film

Mass Transfer and Separation carries 8–12 questions, and no other FE exam has it as a knowledge area. Equimolar counter-diffusion is one line in the handbook. What is being tested is whether you pick that line, and whether you can carry partial pressures and a temperature through it in consistent units.

2
medium
A. Molecular & convective diffusion
Components A and B of a binary gas mixture diffuse in opposite directions at equal molar rates (equimolar counter-diffusion) across a gas film 2 mm thick at 100 °C and 101.3 kPa. The partial pressure of A is 20 kPa at one face of the film and 5 kPa at the other, as shown, and the mass diffusivity of A in B is $D_m = 2.0\times10^{-5}$ m²/s. The molar flux of A across the film is most nearly:
Figure — drag or pinch to move around
1. 0.0484 mol/(m²·s)
2. 0.0553 mol/(m²·s)
3. 0.0645 mol/(m²·s)
4. 0.180 mol/(m²·s)
Show the answer & worked solution
Answer: A.0.0484 mol/(m²·s)
For equimolar counter-diffusion of gases the FE Handbook (Chemical Engineering — Mass Transfer, p. 249) gives $N_A = \dfrac{D_m}{RT}\cdot\dfrac{p_{A1}-p_{A2}}{\Delta z}$ . With $T = 100 + 273.15 = 373.15$ K, $\Delta z = 0.002$ m and $p_{A1}-p_{A2} = 15000$ Pa: $N_A = \dfrac{(2.0\times10^{-5})(15000)}{(8.314)(373.15)(0.002)}$ = 0.0484 mol/(m²·s). Distractors: the STAGNANT-B formula (p. 248), which multiplies by $P/(p_B)_{lm} = 101.3/88.6$ : it holds only when B does not diffuse, 0.0553 mol/(m²·s); $p_{A1}$ alone used as the driving force ( $p_{A2}$ ignored), 0.0645 mol/(m²·s); and $T$ left in degrees Celsius (100 instead of 373.15 K), 0.180 mol/(m²·s).

What the distractors teach

With T = 373.15 K, the film 0.002 m thick and a driving force of 15,000 Pa, N_A = (2.0 × 10⁻⁵)(15,000) / [(8.314)(373.15)(0.002)] = 0.0484 mol/(m²·s). The handbook prints a second flux formula one page earlier, for a gas diffusing through a stagnant gas, and it gives 0.0553: right arithmetic, wrong physics, because here B diffuses back at the same molar rate. Leave the temperature in Celsius and you get 0.180, almost four times too large. Use the upstream partial pressure alone and you get 0.0645. Diffusion is driven by a difference, converted to concentration with R·T in kelvin.

3. Percent overshoot of an under-damped loop

Process Control is only 4–6 questions, so it is easy to under-prepare. The overshoot formula is printed in the handbook, and every wrong answer here is a way of copying it down wrong.

3
medium
A. Process dynamics & transfer functions
A closed-loop pressure controller is tuned so that the loop responds to a set-point change as an under-damped second-order system with damping ratio $\zeta = 0.5$ . The percent overshoot of its response to a step change in set point is most nearly:
Figure — drag or pinch to move around
1. 2.66 %
2. 16.3 %
3. 20.8 %
4. 25.7 %
Show the answer & worked solution
Answer: B.16.3 %
For an under-damped second-order response the FE Handbook (Instrumentation, Measurement, and Control, p. 233) gives the percent overshoot as $\%OS = 100\,e^{-\zeta\pi/\sqrt{1-\zeta^2}}$ . Here $\sqrt{1-\zeta^2} = \sqrt{1-0.5^2} = 0.866$ , the exponent is $0.5\pi/0.866 = 1.814$ , and $\%OS = 100\,e^{-1.814}$ = 16.3 %: the first peak rises 16.3 % of the total change above the final value. Distractors: the DECAY RATIO (ratio of successive peaks, the overshoot fraction squared) reported, $100e^{-2\zeta\pi/\sqrt{1-\zeta^2}}$ = 2.66 %; the $\sqrt{1-\zeta^2}$ dropped, $100e^{-\pi\zeta}$ = 20.8 %; and the root MULTIPLYING instead of dividing, $100e^{-\zeta\pi\sqrt{1-\zeta^2}}$ = 25.7 %.

What the distractors teach

For ζ = 0.5, √(1 − ζ²) = 0.866, the exponent is 0.5π/0.866 = 1.814, and the overshoot is 100e^(−1.814) = 16.3%. Leave the √(1 − ζ²) out of the exponent altogether and you get 20.8%. Multiply by it instead of dividing and you get 25.7%. Those are about 28% and 57% too high, and both look perfectly reasonable on the page. The fourth option, 2.66%, is the decay ratio, the overshoot squared: a real number from the same response, measured one cycle later, and not what was asked. The formula is in the book. The skill is copying the exponent exactly.

Where the 110 questions come from

Seventeen knowledge areas, more than FE Civil, FE Mechanical or FE Other Disciplines carry. The four marked below have no matching knowledge area on any of the other five FE specifications. FE Environmental does touch reactors, kinetics and some separation processes as subtopics.

FE Chemical knowledge areas and question counts, per the NCEES specification effective July 2020
Knowledge area	Questions
MathematicsAnalytic geometry, calculus, differential equations, numerical methods.	6–9
Probability and StatisticsDistributions, expected value, hypothesis testing, regression, data quality.	4–6
Engineering SciencesBasic dynamics, work, energy and power, and the electrical basics: charge, current, voltage, Ohm's and Kirchhoff's laws.	4–6
Materials ScienceChemical and physical properties, corrosion, polymers, material selection.	4–6
Chemistry and BiologyInorganic and organic chemistry, stoichiometry, equilibrium, kinetics, biological processes.	7–11
Fluid Mechanics/DynamicsFluid properties and statics, energy and continuity, pipe flow and fittings, pumps, compressible flow, non-Newtonian fluids.	8–12
ThermodynamicsLaws, properties and phase behavior, cycles, mixtures, chemical equilibrium.	8–12
Material/Energy BalancesThe largest area on the exam. Steady and unsteady balances, recycle and bypass, reactive systems.	10–15
Heat TransferConduction, convection, radiation, heat-transfer coefficients, heat exchanger design (LMTD, NTU).	8–12
Mass Transfer and SeparationChemE onlyDiffusion, distillation, absorption, extraction, membranes, humidification and drying. FE Environmental touches a few separation processes (adsorption, membranes, air stripping) inside its water treatment area, but no other FE exam has mass transfer as a knowledge area.	8–12
Solids HandlingChemE onlyParticle properties and size distributions, crushing, grinding and crystallization, conveying and storage. Small, and on no other FE specification.	3–5
Chemical Reaction EngineeringChemE onlyRate laws, the Arrhenius rate constant, batch, CSTR and plug-flow reactors, conversion, yield and selectivity, catalysis. FE Environmental lists reactors and kinetics as subtopics, but no other exam gives them a whole area.	7–11
EconomicsTime value of money, cost estimation, project evaluation, depreciation.	4–6
Process DesignChemE onlyProcess flow diagrams and P&IDs, equipment sizing and scale-up, cost estimation, optimization, design standards. Unique to this exam.	7–11
Process ControlDynamics, feedback and feedforward, controller tuning, stability. FE Mechanical, FE Electrical and FE Other all examine control too, under other names.	4–6
Safety, Health, and EnvironmentHazard recognition, exposure limits, process safety, emissions and waste.	5–8
Ethics and Professional PracticeCodes of ethics, professional liability, licensure, agreements.	3–5

One row is worth reading carefully. Material/Energy Balances is the largest area on the exam, and it is NOT in the ChemE-only list: FE Environmental examines mass and energy balances under three of its own areas. The four badged above are the ChemE-only areas, and Solids Handling among them is tied with Ethics for the smallest area on the exam at 3 to 5 questions. Small does not mean skippable when the whole exam is 110.

For the pass-rate picture across all seven FE disciplines, the companion guide covers it: how hard is the FE exam?

Common questions

What do FE Chemical practice problems actually look like?: Mostly multiple choice with four options, usually phrased 'most nearly', and the options sit close enough that you cannot eliminate them by inspection. In the diffusion problem below, the right answer and the result of the handbook's formula for a different situation are 14% apart. Many carry a figure: a process flow sketch, a stress element, a concentration profile, a sieve curve. NCEES gives 110 questions in a 6-hour appointment, of which 5 hours 20 minutes is exam time, so the working time per question is under three minutes once you allow for reading, a handbook lookup and a check. NCEES also uses alternative item types (multiple correct answers, point-and-click, drag-and-drop and fill-in-the-blank), each scored right or wrong with no partial credit.
What is on the FE Chemical exam that is not on any other FE exam?: Four knowledge areas: Mass Transfer and Separation at 8-12 questions, Chemical Reaction Engineering at 7-11, Process Design at 7-11, and Solids Handling at 3-5. None of the five other FE specifications has an area for any of them. Process Design and Solids Handling appear nowhere else at all; FE Environmental does list reactors, kinetics and a few separation processes (adsorption, membranes, air stripping) as subtopics. Together the four areas carry 25 to 35 of the 110 questions; their maxima add to 39, but the other 13 areas' minimums already take 75. Material/Energy Balances, the largest area here, is not in that list: FE Environmental lists mass and energy balances under three of its own areas.
How many questions are on each FE Chemical topic?: Material/Energy Balances is the largest at 10-15. Fluid Mechanics/Dynamics, Thermodynamics, Heat Transfer, and Mass Transfer and Separation follow at 8-12 each; Chemistry and Biology, Chemical Reaction Engineering, and Process Design at 7-11 each; Mathematics 6-9; Safety, Health and Environment 5-8; Probability and Statistics, Engineering Sciences, Materials Science, Economics and Process Control 4-6 each; Solids Handling and Ethics and Professional Practice 3-5 each. That is 17 knowledge areas, more than FE Civil, Mechanical or Other Disciplines carry, and the ranges sum to between 100 and 153 against an exam of 110.
Is FE Chemical harder than the other FE exams?: Different rather than harder, and the difference is specialization rather than difficulty. No single area dominates: the largest, Material/Energy Balances at 10-15 questions, is the same size as the largest areas on FE Civil and FE Mechanical. But roughly a quarter to a third of the questions come from subjects most candidates meet only on a chemical engineering degree. Whether that makes it harder depends entirely on what you studied.
What reference material do you get on the FE Chemical exam?: The exam is closed book with an electronic reference: the NCEES FE Reference Handbook is supplied on-screen as a searchable PDF, and no personal copies or outside material are allowed. Practice with the searchable PDF rather than a printed copy. With 17 knowledge areas to move between, finding the right page quickly is a substantial part of the skill being tested.

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Format, knowledge areas and appointment length are from the NCEES FE Chemical specification effective beginning with the July 2020 examinations. The per-question time and the comparisons drawn against other FE specifications are ours, not NCEES figures. Specifications and fees change over time; confirm current specifics at ncees.org. Independent study resource; not affiliated with, endorsed by, or sponsored by NCEES.