Question

Which one of the following thermodynamic quantities is not a state function?
1. Gibbs free energy
2. Enthalpy
3. Entropy
4. Work

Answer 1

Correct Answer - Option 4 : Work

Explanation:

• State functions depend only on the state of the system, not on the path used to get to that state.
• Temperature is a state function.
• No matter how many times we heat, cool, expand, compress, or otherwise change the system, the net change in the temperature only depends on the initial and final states of the system.

ΔT = T_final - T_initial

• The same can be said for the volume, pressure, and the number of moles of gas in the sample. These quantities are all state functions.
• Heat and work are not state functions.
• Work can not be a state function because it is proportional to the distance an object is moved, which depends on the path used to go from the initial to the final state.
• If work is not a state function, then heat ca not be a state function either.
• According to the first law of thermodynamics, the change in the internal energy of a system is equal to the sum of the heat and the work transferred between the system and its surroundings.

So, work is not a state function.