Question

Which one is true for internal energy?

(a) It is sum of all forms of energies associated with molecules of a system

(b) It is a state function of a system

(c) It is proportional to transnational K.E of the molecules

(d) All of the mentioned

I have been asked this question during a job interview.

Asked question is from Internal Energy topic in division Energy Balances of Chemical Process Calculation

Answer 1

To answer this, let's examine each option in the context of internal energy:

1. (a) It is the sum of all forms of energies associated with molecules of a system:
   This is true. Internal energy includes the total of all kinetic and potential energies of the molecules, such as translational, rotational, vibrational, and intermolecular energy.

2. (b) It is a state function of a system:
   This is also true. Internal energy is a state function, meaning it depends only on the current state of the system (e.g., temperature, pressure, volume), not on how the system reached that state.

3. (c) It is proportional to the translational kinetic energy of the molecules:
   This is partially true. For an ideal gas, the internal energy is directly related to the translational kinetic energy of the molecules. However, for real gases and other states of matter, other forms of energy also contribute to the internal energy.

4. (d) All of the mentioned:
   Since all the options are correct under different contexts, this answer is the most accurate.

Correct Answer: (d) All of the mentioned