Thermodynamics Questions

Thermodynamics is a branch of science that studies the concepts of heat and temperature and the inter-conversion of heat and other forms of energy. The term thermodynamics was coined in 1749 by William Thomson. Thermodynamics is a macroscopic science that is divided into

chemical thermodynamics, statistical thermodynamics, equilibrium thermodynamics, and classical thermodynamics.

The types of thermodynamic systems are:

• Open System
• Closed System
• Isolated System

When changes in volume, pressure and internal energy occur, a system experiences a thermodynamic process. Thermodynamic processes are the movement of heat energy within or between systems. Factors that take place out of the system and those that impact the system’s behaviour are referred to as a surrounding.

• Adiabatic Process – no heat transfer occurs in or out of the system.
• Isochoric Process – no volume change occurs, and this system does not work.
• Isobaric Process – no pressure change takes place.
• Isothermal Process – no temperature change takes place.

Note:

Enthalpy is the measurement of energy in a thermodynamic system.

Calculation of energy in a thermodynamic system gives enthalpy and its formula is:

H = E + PV

The thermodynamic value is dependent on the physical state of a system known as the entropy. The measure of the stored energy in a system is given by the thermodynamic potential.

Internal Energy of the thermodynamics system is given by

U=∫TdS−PdV + ∑iμidNi

Helmholtz free energy: F = U – TS

Enthalpy: H = U + PV

Gibbs Free Energy: G = U + PV – TS

Important Thermodynamics Questions with Answers

1. Helmholtz free energy is given by the formula ______

1. F = U + TS
2. F = U * TS
3. F = U/TS
4. F = U – TS

Answer: d) F = U – TS

Explanation: Helmholtz free energy is given by the formula F = U – TS

2. Entropy is defined in which law of thermodynamics?

1. Zeroth
2. First
3. Second
4. Third

Answer: c) Second

Explanation: Entropy is defined in the second law of thermodynamics.

3. Match the following:

1. Adiabatic Process   i) no volume change takes place
2. Isochoric Process   ii) no pressure change takes place.
3. Isobaric Process   iii) no temperature change takes place.
4. Isothermal Process   iv) no heat transfer takes place.

Options:

1. a)-iv b) iii c) ii d) i
2. a)-i b) iv c) ii d) iii
3. a)-iv b) i c) ii d) iii
4. a)-i b) ii c) iii d) iv

Answer: 3) a)-iv b) i c) ii d) iii

4. Fill in the blanks: _____ coined the term thermodynamics.

Answer: William Thomson

Explanation: The term thermodynamics was coined by William Thomson in 1749.

5. State true or false: Thermodynamic potentials are quantitative measures of the external energies associated with the system.

1. TRUE
2. FALSE

Answer: b) FALSE

Explanation: Thermodynamic potentials are quantitative measures of the stored energy in a system.

6. The entropy of a system approaches a constant value as the temperature ______

1. Increases
2. Decreases
3. Approaches absolute zero
4. None of the options

Answer: c) Approaches absolute zero.

Explanation: According to the third law of thermodynamics, the constant value is approached by the system when the temperature approaches absolute zero.

7. What are the branches of thermodynamics?

Branches of thermodynamics are:

• Classical Thermodynamics
• Statistical Thermodynamics
• Chemical Thermodynamics
• Equilibrium Thermodynamics

8. A thermodynamic system undergoes ______

1. Changes in pressure
2. Changes in volume
3. Changes in internal energy
4. All the above options

Answer: d) All the above options.

Explanation: A thermodynamic system undergoes changes in pressure, volume, and internal energy.

9. The measurement of energy in a thermodynamic system is referred to as ______

1. Enthalpy
2. Entropy
3. Equilibrium
4. None of the options

Answer: a) Enthalpy

Explanation: Enthalpy is the measurement of energy in a thermodynamic system.

10. Internal Energy of the thermodynamics system is given by the formula ______

1. U=∫TdS−PdV
2. U=∫TdS−PdV-∑iμidNi
3. U=∫TdS−PdV+∑iμidNi
4. U=∫TdS+PdV+∑iμidNi

Answer: c) U=∫TdS−PdV+∑iμidNi

Practice Questions

1. Define thermodynamics.
2. What are the types of thermodynamic systems?
3. Give the formula to find Gibbs free energy.
4. Which law of thermodynamics states that “the entropy of a system approaches a constant value as the temperature approaches absolute zero”?.
5. The process where no heat transfer in or out of the system occurs is known as ______

1. Adiabatic Process
2. Isochoric Process
3. Isobaric Process
4. Isothermal Process

Watch the video below to understand thermodynamic devices in detail.