key term - ΔG < 0

Definition

The change in Gibbs free energy (ΔG) being less than 0 indicates that a chemical reaction or process is thermodynamically favorable and will occur spontaneously. This term is particularly important in the context of understanding the driving forces behind chemical reactions and the feasibility of various processes.

5 Must Know Facts For Your Next Test

1. When ΔG < 0, the reaction or process is thermodynamically favorable and will occur spontaneously, releasing energy in the form of heat or work.
2. A negative ΔG indicates that the products of the reaction have a lower Gibbs free energy than the reactants, driving the reaction forward.
3. The magnitude of ΔG determines the extent of the spontaneity and the amount of energy released or required for the reaction.
4. Reactions with ΔG < 0 are considered exergonic, meaning they release energy, while reactions with ΔG > 0 are endergonic, meaning they require an input of energy.
5. The value of ΔG is influenced by changes in enthalpy (ΔH) and entropy (ΔS) according to the equation: ΔG = ΔH - TΔS.

Review Questions

• Explain the significance of ΔG < 0 in the context of chemical reactions and processes.
  • When the change in Gibbs free energy, ΔG, is less than 0, it indicates that the reaction or process is thermodynamically favorable and will occur spontaneously. This means that the products of the reaction have a lower Gibbs free energy than the reactants, and the reaction will release energy in the form of heat or work. The magnitude of the negative ΔG value determines the extent of the spontaneity and the amount of energy released. Reactions with ΔG < 0 are considered exergonic and are driven by the tendency of the universe to increase in entropy.
• Describe how the values of enthalpy (ΔH) and entropy (ΔS) influence the sign and magnitude of ΔG.
  • The value of ΔG is determined by the changes in enthalpy (ΔH) and entropy (ΔS) according to the equation: ΔG = ΔH - TΔS. When ΔG < 0, it means that the decrease in enthalpy (ΔH < 0, indicating an exothermic reaction) and/or the increase in entropy (ΔS > 0, indicating an increase in disorder) are the driving forces behind the spontaneity of the reaction. The magnitude of the negative ΔG value depends on the relative contributions of ΔH and TΔS, with larger negative values indicating a more favorable and spontaneous process.
• Analyze the relationship between ΔG < 0 and the thermodynamic feasibility of a chemical reaction or process.
  • The condition of ΔG < 0 is directly linked to the thermodynamic feasibility of a chemical reaction or process. When ΔG is less than 0, it indicates that the reaction or process is thermodynamically favorable and will occur spontaneously, as the products have a lower Gibbs free energy than the reactants. This means that the reaction or process is thermodynamically feasible and can occur naturally without the input of external energy. Conversely, if ΔG > 0, the reaction or process is thermodynamically unfavorable and will not occur spontaneously, requiring an input of energy to proceed. Therefore, the sign and magnitude of ΔG provide a clear assessment of the thermodynamic feasibility of a given chemical system or process.

Related terms

Gibbs Free Energy (G): A thermodynamic quantity that combines the internal energy of a system, the work done by or on the system due to pressure-volume changes, and the disorder or randomness (entropy) of the system.

Spontaneous Process:

A process that occurs naturally without the input of external energy, driven by the tendency of the universe to increase in entropy.

Thermodynamic Feasibility: The assessment of whether a chemical reaction or process is possible based on the changes in Gibbs free energy, enthalpy, and entropy.