3.1.8.4 Gibbs Free Energy

• What does entropy ($\Delta S$) measure?


  Disorder or randomness
• What does Gibbs Free Energy (ΔG) measure?

  Energy available for useful work
• Temperature in the Gibbs Free Energy equation must be in Kelvin.

  True
• If ΔG is negative, the reaction is spontaneous.


  True
• What is the unit for temperature in the Gibbs Free Energy equation?

  Kelvin
• What does the sign of ΔG indicate about the spontaneity of a reaction?

  ΔG < 0: Spontaneous ||| ΔG > 0: Non-spontaneous ||| ΔG = 0: Equilibrium
• The formula for Gibbs Free Energy is \Delta G = \Delta H - T\Delta S
• ΔS in the Gibbs Free Energy equation represents the entropy change, which is the change in disorder or randomness.


  True
• What does a ΔG value of zero indicate about a reaction?

  Equilibrium
• In what unit is the absolute temperature (T) measured in the Gibbs Free Energy equation?

  Kelvin
• Match the ΔG value with the corresponding spontaneity:

  ΔG < 0 ↔️ Spontaneous

  ΔG > 0 ↔️ Non-spontaneous

  ΔG = 0 ↔️ At equilibrium
• Entropy (ΔS) measures the disorder or randomness in a system.


  True
• What is the spontaneity of a reaction if ΔG > 0?

  Non-spontaneous
• A negative ΔG value indicates that a reaction will occur without external energy input.


  True
• Exothermic reactions have a negative ΔH value.


  True
• The melting of ice is an endothermic process.


  True
• Exothermic reactions release heat to the surroundings.
• Exothermic reactions have a negative enthalpy change ($\Delta H < 0$).


  True
• What does entropy (\Delta S</latex>) measure?

  Disorder or randomness
• Temperature in Kelvin is crucial in determining the spontaneity of a reaction using the Gibbs Free Energy equation.


  True
• To calculate changes in Gibbs Free Energy, we use the formula $\Delta G =$$\Delta H - T\Delta S$, where $T$ is the temperature in Kelvin.
• A negative $\Delta G$ indicates a spontaneous reaction.


  True
• What does a positive $\Delta G$ indicate about the spontaneity of a reaction?


  Non-spontaneous
• What is the equation for Gibbs Free Energy (ΔG)?

  $\Delta G =$$\Delta H - T\Delta S$
• What does ΔS represent in the Gibbs Free Energy equation?


  Entropy change
• What is the value of ΔH in the example reaction?

  -100 kJ/mol
• What does the Gibbs Free Energy (ΔG) measure?

  Energy available for work
• What does ΔS represent in the Gibbs Free Energy equation?


  Change in disorder
• What is the calculated value of ΔG in the example reaction at 298 K?

  -159.6 kJ/mol
• The overall energy available for useful work is called Gibbs Free Energy
• Entropy measures the change in disorder or randomness
• What is the value of ΔG for a reaction with ΔH = -100 kJ/mol and ΔS = 200 J/mol·K at T = 298 K?

  -159.6 kJ/mol
• What is the formula for calculating enthalpy change?

  $ΔH =$$H_{\text{products}} - H_{\text{reactants}}$
• Entropy measures the disorder or randomness in a system
• What is the mathematical formula for entropy change?

  ΔS = S_{\text{products}} - S_{\text{reactants}}</latex>
• Low temperatures favor reactions with negative ΔH

  True
• The formula for calculating Gibbs Free Energy is \Delta G
• To convert ΔS from J/mol·K to kJ/mol·K, you divide by 1000.


  True
• What is the value of ΔS in the example reaction?

  300 J/mol·K
• What does a negative value of ΔG indicate about a reaction?

  Spontaneous