Chemical Engineering Questions

Chemical engineers use mathematics, physical sciences, life sciences and economics to create, produce, convert, transport, utilise and supervise the industrial processes that turn raw materials into useful products.

Chemical Engineering Chemistry Questions with Solutions

Q1. What is the internal energy change over an entire cycle in a cyclic process?

1. Zero
2. Positive
3. Dependent on the path
4. Can’t be determined
5. None of the above

Answer: (a), The internal energy change over an entire cycle in a cyclic process is zero.

Q2. Which of the following is not an intensive property?

1. Chemical potential
2. Surface tension
3. Heat capacity
4. None of these

Answer: ©, Heat capacity is not an intensive property.

Explanation: An intensive property is a property of matter whose value does not depend on the quantity of the substance. Quantities like chemical potential and surface tension do not rely on the amount of the substance and therefore are intensive properties. In contrast, heat capacity depends on its mass and chemical composition and, therefore, is an extensive property.

Q3. One Newton is equal to __________ dynes.

1. 10⁵
2. 10⁴
3. 10³
4. 10²

Answer: (a), One Newton equals 10⁵ dynes.

Q4. Which of the following is generally considered an opaque surface toward radiations?

1. Solids
2. Liquids
3. Gases
4. Both (a) and (b)
5. Both (b) and ©

Answer: (d), Both solids and liquids are generally considered an opaque surfaces toward radiations.

Q5. Which of the following will give maximum gas conversion?

1. Semi-fluidised bed reactor
2. Plug-flow catalytic reactor
3. Fixed bed reactor
4. Fluidised bed reactor

Answer: (a), A semi-fluidised bed reactor gives maximum gas conversion.

Q6. What is Gibbs free energy?

Answer: Gibbs free energy is a thermodynamic quantity used to determine the maximum amount of work done when the temperature and pressure are constant. It is also known as the Gibbs function or free enthalpy. It is denoted by the sign ‘G’.

It is equivalent to

Δ G = Δ H − T ΔS

Q7. What is an isochoric process?

Answer: In thermodynamics, an isochoric process is a process in which the volume remains constant. It is also referred to as a constant-volume process or isometric process.

As the volume is constant, the work done in an isochoric process is zero.

W = P Δ V

Here, Δ V = 0

So, W = 0

Q8. What happens when the paint dries?

Answer: While manufacturing paints, additives are added to make paint thin. After the application of paint, the additives get evaporated, and the pigments and resins are converted to a hard, tough, cross-linked film that persists in hardening forever.

Q9. What is carbon sequestration?

Answer: Carbon sequestration is a method for grabbing and storing atmospheric carbon dioxide. The primary objective of carbon sequestration is to reduce global climate change.

Q10. What is the black body?

Answer: A black body is an ideal object competent for absorbing all electromagnetic radiation it receives without reflecting anything.

Q11. What are the disadvantages of PFR?

Answer: PFR is the abbreviation of plug flow reactor. It is used to illustrate chemical reactions in a continuously flowing system.

Disadvantages of PFR:

• Temperature is hard to control in the PFR model.
• Undesirable temperature gradients are observed while handling the PFR model.
• The maintenance of the PFR model is much more than the CSTR model

Q12. What is quicklime? Mention a few applications of quick lime.

Answer: Quicklime is the common name for calcium oxide (CaO).

There is a lot of application of quicklime. Few of them are enlisted below.

• It is used in the production of iron and steel.
• It is used in the production of paper and pulp.
• It is used in the treatment of water and flue gases.
• It is used in whitewashing.

Q13. What are the laws of thermodynamics?

Answer: There are three laws of thermodynamics. It states that

• Law One: Energy can neither be created nor be destroyed. It can only be transmitted from one form to another.
• Law Two: The entropy of an isolated system is increasing continuously.
• Law Three: The entropy of a system approaches a constant value as the temperature approaches its absolute zero.
• Zeroth Law: If two bodies are in thermal equilibrium with a third body. Then they are in thermal equilibrium with each other.

Q14. Differentiate between unit operation and unit process.

Answer:

Q15. What are scales and sludge?

Answer: In the boiler, evaporation and concentration of dissolved salts rise constantly. On reaching the point of saturation, they are precipitated on the internal walls of the boiler. If the sediment is loose and skimmy, it is known as sludge. In contrast, if the residue is hard adhering crust, it is known as scales.

Sludge is slimy, soft and lose residue formed in the colder portions of the boiler. It is formed by substances that have greater solubility in hot water. Example: Magnesium carbonate, magnesium chloride, calcium chloride and magnesium sulphate.

Practise Questions on Chemical Engineering

Q1. If the pH value of an acidic solution is decreased from 5 to 2, then the increase in its hydrogen ion concentration is __________ times.

1. 10
2. 100
3. 1000
4. 10000

Q2. What are the disadvantages of sludge formation?

Q3. Give an example of negative work?

Q4. What are PCBs?

Q5. What is the primary function of a three-way catalytic converter?

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