Enthalpy Questions

Thermodynamics is the branch of physics that deals with the relationships between heat and other forms of energy. We have heard of various thermodynamic parameters in our previous sessions, and enthalpy is one of them. Enthalpy (H) is the sum of the internal energy (U) and the product of pressure (P) and volume (V). It is also known as heat content.

It is given by the formula: H = U + pV

V = Volume of the system

p = Pressure of the system

H = Enthalpy of the system

U = Internal energy of the system

The SI unit of enthalpy is joule.

Enthalpy is expressed as:

H = Energy/Mass

The enthalpy of vaporization is defined as the energy that needs to be added to a material to change its phase from a liquid to a gas. The enthalpy of vaporization is expressed in units of joules per mole.

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Important Enthalpy Questions with Answers

1. The internal energy of the system is represented by ______.

1. V
2. U
3. P
4. H

Answer: b) U

Explanation: Internal energy of the system is represented by the letter U.

2. How is enthalpy represented?

1. H = Energy + Mass
2. H = Energy – Mass
3. H = Energy/Mass
4. H = Energy × Mass

Answer: c) H = Energy/Mass

Explanation: Enthalpy is represented as H = Energy/Mass.

3. The SI unit of enthalpy is _____.

1. Watt
2. Joule
3. Radians
4. Kilogram

Answer: b) Joule

Explanation: The SI unit of enthalpy is joule.

4. Which among the following is a secondary dimension?

1. Mass
2. Time
3. Length
4. Velocity

Answer: d) Velocity

Explanation: Mass, Time, and Length are the primary dimensions. Velocity is the secondary dimension.

5. 10¹² represents ______.

1. Giga
2. Centi
3. Tera
4. Nano

Answer: c) Tera

Explanation: 10¹² represents tera and is indicated as T.

6. ______ is the branch of physics that deals with the relationships between heat and other forms of energy.

1. Ophthalmology
2. Mechanics
3. Optics
4. Thermodynamics

Answer: d) Thermodynamics

Explanation: Thermodynamics is the branch of physics that deals with the relationships between heat and other forms of energy.

7. Which among the following is a primary dimension?

1. Velocity
2. Length
3. Pressure
4. Acceleration

Answer: b) Length

Explanation: Length is a primary dimension among the following options.

8. Enthalpy of vaporization is expressed in units of ______.

1. Watts per second
2. Radians per mole
3. Joules per mole
4. Kilowatts

Answer: c) Joules per mole

Explanation: The enthalpy of vaporization is expressed in units of joules per mole.

9. As per the law of thermodynamics, during an interaction, energy can change from one form to another, but the total amount of energy _____.

1. Increases
2. Decreases
3. Remains Constant
4. Becomes Zero Always

Answer: c) Remains Constant

Explanation: The total energy remains constant when energy can change from one form to another.

10. Is the law of thermodynamics applied in air-conditioning systems?

1. YES
2. NO

Answer: a) YES

Explanation: Where ever the interaction between energy and matter is seen, thermodynamics is involved. Hence in the air-conditioning systems, the law of thermodynamics is applied.

Practice Questions

1. State first law of thermodynamics.
2. What is thermodynamics?
3. Define enthalpy.
4. What is the formula to find enthalpy?
5. What is the unit to measure enthalpy?