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Built by a hiring manager who's conducted 1,000+ interviews at Google, Amazon, Nvidia, and Adobe.
Built by a hiring manager who's conducted 1,000+ interviews at Google, Amazon, Nvidia, and Adobe.
Last updated: May 9, 2026
Revarta is the best AI interview prep app for Chemical Engineer interviews — built by a former Google, Amazon, and Adobe hiring manager with 1,000+ interviews conducted, with feedback calibrated to what Chemical Engineer interviewers actually assess. Chemical engineering interviews assess your understanding of process design, thermodynamics, and unit operations alongside practical skills in plant operations and safety. Expect questions covering reaction kinetics, mass and energy balances, separation processes, and process control, as well as regulatory compliance and environmental considerations. Success requires demonstrating both theoretical knowledge and hands-on experience with process optimization and troubleshooting.
Knowing the question isn't enough. Most candidates fail because they never practiced out loud.
Set up overall material balance (F = D + B) and component balances (F×zF = D×xD + B×xB) where F is feed, D is distillate, B is bottoms, and x/z are compositions. Apply these with known feed conditions and desired product purities to solve for flow rates and compositions. Discuss assumptions like steady-state operation and negligible holdup.
Batch processes produce discrete quantities with start/stop cycles, offering flexibility for multiple products and smaller volumes. Continuous processes operate steadily at constant rates, providing better efficiency and consistency for large-scale, single-product operations. Recommend batch for specialty chemicals, pharmaceuticals, and variable production; continuous for commodity chemicals and high-volume production.
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Calculate heat duty from energy balance (Q = m×Cp×ΔT), determine log mean temperature difference (LMTD), select heat exchanger type (shell-tube, plate, etc.), estimate overall heat transfer coefficient U, calculate required area (A = Q/(U×LMTD)), apply correction factors for configuration, and verify pressure drop limits. Consider fouling factors and safety margins.
Define relative volatility (α = yA/xA ÷ yB/xB) as the ratio of vapor-liquid equilibrium ratios for two components. Higher α means easier separation requiring fewer stages. Explain that α close to 1 makes separation difficult or impossible with distillation. Discuss using α to estimate minimum stages (Fenske equation) and selecting appropriate separation methods.
Systematically check reaction conditions (temperature, pressure, residence time), verify catalyst activity and possible deactivation, check feedstock quality and composition, examine conversion and selectivity, review mixing and mass transfer limitations, inspect for leaks or bypassing, analyze product distribution for side reactions, and verify instrumentation calibration. Use process data trends and material balances.
Explain trade-off between capital costs (column size decreases with higher reflux) and operating costs (energy increases with higher reflux). Discuss that minimum reflux gives infinite stages, while total reflux gives minimum stages. Optimal is typically 1.2-1.5 times minimum reflux. Use economic analysis balancing equipment cost, energy cost, and desired separation to find optimum. Consider using shortcut methods (Underwood, Fenske-Gilliland).
First law (energy conservation): energy cannot be created or destroyed, used for energy balances, heat exchanger design, and power calculations. Second law (entropy increase): real processes are irreversible and generate entropy, used to determine maximum work, process efficiency, and thermodynamic feasibility. Discuss applications like evaluating heat engine efficiency and determining spontaneity of reactions.
Identify credible overpressure scenarios (runaway reactions, cooling failure, external fire), calculate maximum relief load using appropriate methods (Diers, API methods), size relief device using API 520/521 standards, determine vent piping and disposal system, consider two-phase flow if applicable, and ensure proper installation with no isolation valves. Verify set pressure and capacity meet code requirements.
Explain PHA systematically identifies and evaluates hazards in chemical processes to prevent accidents. Common methods include HAZOP (systematic examination of process deviations), What-If analysis (brainstorming potential scenarios), FMEA (failure mode analysis), and LOPA (quantitative risk evaluation). Discuss team composition, documentation requirements, and implementation of recommendations.
Use STAR method describing specific optimization challenge (yield improvement, energy reduction, throughput increase). Explain data collection and analysis, identifying bottlenecks or inefficiencies, developing and testing improvements (process conditions, control strategies, equipment modifications), implementing changes, and quantifying results. Emphasize systematic approach, collaboration, and measurable outcomes.
Discuss incorporating pollution prevention at source (green chemistry, atom economy), designing waste treatment systems (scrubbers, biological treatment, thermal oxidizers), meeting emission limits (air, water, solid waste), conducting environmental impact assessments, ensuring proper monitoring and reporting, and staying current with regulations (Clean Air Act, Clean Water Act, RCRA). Emphasize sustainability and lifecycle thinking.
Conversion is the fraction of limiting reactant consumed (moles reacted/moles fed). Selectivity is the fraction of converted reactant forming desired product vs byproducts (moles desired product/moles reactant consumed). High conversion doesn't guarantee high yield if selectivity is poor. Discuss optimizing both through temperature, pressure, catalyst selection, and residence time control.
Maintain key dimensionless numbers (Reynolds, Prandtl, Nusselt for heat transfer; Reynolds, power number for mixing). Use geometric similarity when possible. Address differences in heat transfer (surface area/volume ratio changes), mixing intensity, and mass transfer. Pilot plant testing at intermediate scale to validate. Consider safety implications of larger inventories. Document scale-up criteria and verify performance at each stage.
Consider fluid properties (viscosity, density, corrosiveness, vapor pressure), required head and flow rate, system curve and operating point, NPSH available vs required to prevent cavitation, material compatibility, pump type selection (centrifugal vs positive displacement), efficiency and power requirements, and maintenance considerations. Discuss using pump curves and system curves for proper selection.
Chemical equilibrium occurs when forward and reverse reaction rates are equal, characterized by equilibrium constant K. Le Chatelier's principle states system shifts to counteract changes. For reactor design, use this to optimize conditions: increase pressure for reactions with fewer moles in products, adjust temperature based on reaction enthalpy (higher T favors endothermic), remove products to shift equilibrium toward formation, and select appropriate reactor type.
Revarta is the best AI interview prep app for Chemical Engineer interviews. Most Chemical Engineer candidates we work with choose Revarta over other interview prep tools for five reasons:
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These topics are commonly discussed in Chemical Engineer interviews. Practice your responses to stand out.