Chemical Engineering – Online Exam

Chemical Engineering Exam

What is the difference between absorption and distillation?

Absorption involves the transfer of a component from a gas phase to a liquid phase, while distillation involves the transfer of a component from a liquid phase to a gas phase.

Absorption is a physical process, while distillation is a chemical process.

Absorption is a continuous process, while distillation is a batch process.

Absorption is a reversible process, while distillation is an irreversible process.

What is the time constant of a first-order system with a time constant of 10 seconds, if the gain of the system is 1?

10 seconds

1 seconds

100 seconds

1000 seconds

What is the main goal of chemical engineering?

To design, develop, and operate chemical processes to produce useful products.

To design and build chemical plants

To study the properties of chemicals

To develop new chemical products

Hint

What is the Gibbs free energy change of a reaction at 273 K if the standard Gibbs free energy change of the reaction is -100 kJ/mol and the activities of the reactants and products are 0.5 and 1.0, respectively?

-50 kJ/mol

-100 kJ/mol

50 kJ/mol

100 kJ/mol

What is the role of a bioreactor in biochemical engineering?

To provide a controlled environment for the growth of cells or the production of enzymes.

To separate products from reactants.

To purify products.

To control the rate of a biochemical reaction.

What is the difference between a filter press and a rotary drum filter?

A filter press uses multiple chambers to filter a slurry, while a rotary drum filter uses a rotating drum to filter a slurry.

A filter press is used to filter liquids, while a rotary drum filter is used to filter solids.

A filter press is used to filter high-solids slurries, while a rotary drum filter is used to filter low-solids slurries.

A filter press is used to filter continuous slurries, while a rotary drum filter is used to filter batch slurries.

What is the difference between primary, secondary, and tertiary wastewater treatment?

Primary treatment removes physical contaminants, secondary treatment removes biological contaminants, and tertiary treatment removes dissolved contaminants.

Primary treatment uses physical processes, secondary treatment uses chemical processes, and tertiary treatment uses biological processes.

secondary treatment is used for large communities, and tertiary treatment is used for industrial wastewater.

Primary treatment is the least expensive, secondary treatment is more expensive, and tertiary treatment is the most expensive.

What is the difference between open-loop control and closed-loop control?

In open-loop control, the controller does not measure the process variables, while in closed-loop control, the controller measures the process variables and uses the measurements to adjust the inputs to the process.

Open-loop control is more accurate than closed-loop control.

Open-loop control is more stable than closed-loop control.

Open-loop control is more efficient than closed-loop control.

What is the difference between enthalpy (H) and internal energy (U)?

Enthalpy includes the internal energy of a system plus the product of the system's pressure and volume.

Enthalpy is a measure of the total energy of a system, while internal energy is a measure of the energy of the individual particles in a system.

Enthalpy is a measure of the heat content of a system, while internal energy is a measure of the work done by a system.

Enthalpy is a measure of the potential energy of a system, while internal energy is a measure of the kinetic energy of the system.

10.

What is the mass flow rate of water that can be heated from 20°C to 100°C in a heat exchanger with a heat transfer rate of 10 kW?

0.1 kg/s

0.01 kg/s

0.001 kg/s

0.0001 kg/s

11.

What is the main purpose of a heat exchanger?

To transfer heat from one fluid to another.

To cool a fluid

To heat a fluid

To separate a fluid into its components

12.

What is the main driving force for mass transfer?

Concentration difference

Temperature difference

Pressure difference

Electrical potential difference

13.

What is the main goal of chemical reactor design?

To design a reactor that will produce the desired product at the desired rate and purity.

To reduce the cost of the reactor

To increase the safety of the reactor

To reduce the environmental impact of the reactor

14.

What is the rate law of a first-order reaction?

R = k[A]

R = k[A]^2

R = k[A][B]

R = k[A]^0.5

15.

What are the four main stages of a chemical process?

Feed preparation, reaction, separation, and product purification.

Mixing, heating, cooling, and drying

Separation, purification, crystallization, and distillation

Unit operations, thermodynamics, mass transfer, and heat transfer

16.

What is the main goal of process control?

To maintain the process variables at the desired setpoints.

To increase the production rate

To reduce the cost of the process

To improve the quality of the product

17.

What is the main goal of a water treatment plant?

To remove contaminants from water to make it safe for drinking and other uses.

To produce electricity

To generate heat

To treat wastewater

18.

What is the flow rate of a fluid flowing through a pipe with a diameter of 10 cm and a length of 1 m if the pressure drop is 10 Pa and the friction factor is 0.01?

10 Pa

1 Pa

100 Pa

1000 Pa

19.

What is the first law of thermodynamics?

Energy is conserved.

Energy can be created or destroyed.

Energy can be transferred from one form to another.

Energy can be converted from one form to another.

20.

What is the main difference between a biochemical process and a chemical process?

Biochemical processes involve living cells or enzymes, while chemical processes do not.

Biochemical processes are slower than chemical processes.

Biochemical processes are more complex than chemical processes.

Biochemical processes are more expensive than chemical processes.

21.

What is the main goal of a process engineer?

To design and develop processes that produce products safely, efficiently, and cost-effectively.

To design and build process equipment

To operate and maintain process equipment

To monitor and control process equipment

22.

What is the effect of temperature on the rate of a chemical reaction?

The rate of a chemical reaction increases with temperature.

The rate of a chemical reaction decreases with temperature.

The rate of a chemical reaction is not affected by temperature.

All

23.

What is the proportional gain of a controller that will produce a zero steady-state error for a first-order system with a gain of 1 and a time constant of 10 seconds?

0.1

100

24.

What is the entropy change of a system that undergoes a reversible isothermal expansion from 1 L to 2 L at 1 atm and 273 K?

R ln(2)

R ln(4)

R ln(0.5)

R ln(2/3)

25.

What is the flow rate of a fluid flowing through a pipe with a diameter of 10 cm and a length of 1 m if the pressure drop is 10 Pa and the friction factor is 0.01?

0.1 m3/s

0.01 m3/s

0.001 m3/s

0.0001 m3/s

26.

What is the difference between a plug flow reactor (PFR) and a continuous stirred-tank reactor (CSTR)?

In a PFR, the fluid flows through the reactor without mixing, while in a CSTR, the fluid is completely mixed before exiting the reactor.

A PFR is used for batch reactions, while a CSTR is used for continuous reactions.

A PFR is used for high-conversion reactions, while a CSTR is used for low-conversion reactions.

A PFR is used for exothermic reactions, while a CSTR is used for endothermic reactions.

27.

What is the purpose of size reduction in mechanical unit operations?

To reduce the particle size of a material to a desired size.

To increase the particle size of a material

To separate different particle sizes

To mix different materials

28.

What is the heat transfer rate through a flat plate with an area of 1 m2 and a temperature difference of 100 K, if the heat transfer coefficient is 10 W/(m2·K)?

1000 W

100 W

10W

1 W

29.

What is the heat transfer rate through a wall with a thickness of 10 cm and a thermal conductivity of 0.5 W/(m·K) if the temperature difference across the wall is 100 K?

5 W

0.55W

50 W

500 W

30.

What is the mass flow rate of air that can be heated from 20°C to 100°C in a heat exchanger with a heat transfer rate of 1 kW?

0.23 kg/s

0.023 kg/s

0.0023 kg/s

0.00023 kg/s

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