Free Internal Energy MCQs with Answers
2 Internal Energy MCQs from Chemistry, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
2 questions
1. Internal energy of a system is the
- A. heat supplied to the system only
- B. work done by the system only
- C. total of all kinetic and potential energies of the particles in the system
- D. energy lost to the surroundings
Explanation: Internal energy sums the translational, rotational and vibrational energy of the particles together with the potential energy stored in the bonds and intermolecular forces. Its absolute value cannot be measured, but the change in it can, which is all thermodynamics requires. It is a state function, so the change depends only on the initial and final conditions.
Correct answer: total of all kinetic and potential energies of the particles in the system2. In a bomb calorimeter, the heat of reaction measured corresponds to the change in
- A. enthalpy, since the pressure is constant
- B. internal energy, since the volume is constant
- C. entropy
- D. free energy
Explanation: A bomb calorimeter is a sealed rigid vessel, so the volume cannot change, no expansion work is done and all the energy released appears as heat, which equals the change in internal energy. A reaction in an open vessel is at constant pressure and gives the enthalpy change instead. The two differ only by the work done pushing back the atmosphere.
Correct answer: internal energy, since the volume is constant