Sample interview questions: Can you explain the concept of Gibbs free energy and its significance?
Sample answer:
Gibbs free energy is a fundamental concept in thermodynamics that characterizes the equilibrium state of a system. It is denoted by the symbol G and is named after the American scientist Josiah Willard Gibbs. The Gibbs free energy combines two important thermodynamic properties: enthalpy (H) and entropy (S).
The concept of Gibbs free energy is particularly significant because it helps us understand and predict whether a chemical or physical process will occur spontaneously under specific conditions. Spontaneous processes are those that can occur without the need for external intervention.
The Gibbs free energy is defined by the equation:
G = H – TS
where H represents the enthalpy of the system, T is the temperature in Kelvin, and S is the entropy. This equation relates the energy associated with a system’s chemical or physical changes to the temperature and entropy changes that occur during the process.
The significance of Gibbs free energy lies in its ability to determine whether a reaction or process is thermodynamically favorable. If the Gibbs free energy change (ΔG) for a reaction is negative, it indicates that the reaction will occur spontaneously under the given conditions. Conversely, if ΔG is positive, the reaction will not proceed spontaneously.
When ΔG = 0, the system is in a state of equilibrium, meaning that the forward and reverse reactions occur at equal rates. This equilibrium state corresponds to the minimum Gibbs free energy, allowing us to determine the conditions at which a reaction is most stable.
The sign of ΔG also provides insight into the direction of a reaction. When ΔG is negative, the reaction is exergonic, meaning that it releases energy and proceeds in the forward direction. On the other hand, a positive ΔG value indicates an endergonic reaction, which requires an input of energy to proceed … Read full answer