Gibbs Free Energy Quiz

Gibbs Free Energy (ΔG)

• The formula to calculate Gibbs free energy change is ΔG = ΔH - TΔS, where ΔH is the enthalpy change, T is the temperature in Kelvin, and ΔS is the entropy change.

Reaction 1 Analysis

• For reaction 1, ΔS = +200 J/K and ΔH = 600 kJ.
• A positive ΔS suggests an increase in disorder, while the large positive ΔH indicates an input of energy.
• The spontaneity of the reaction cannot be conclusively determined without temperature; however, at high temperatures, the reaction may become spontaneous.

Reaction 2 Analysis

• For reaction 2, ΔS = -200 J/K and ΔH = -600 kJ.
• The negative ΔS indicates a decrease in disorder, while the negative ΔH suggests the reaction releases energy.
• This combination typically favors spontaneity, so the reaction is likely spontaneous.

Reaction 3 Analysis

• Reaction 3: 2N2O(g) + 3O2(g) → 4NO2(g) + 7.9 kJ results in a positive ΔG.
• A positive ΔG indicates that the reaction is non-spontaneous under standard conditions, meaning it requires energy input to proceed.

Reaction 4 Analysis

• Reaction 4: 2 HCl(g) + 185 kJ → H2 Starter(g) + 2 Cl2(g) involves inputting energy (185 kJ).
• The need for energy input generally indicates the reaction is non-spontaneous as written; it will require external energy to occur.