Lecture 02

• What is the concept of spontaneity in thermodynamics?

  It refers to processes that occur naturally.
• What does the third law of thermodynamics state?

  Entropy of a perfect crystal is zero at 0 K.
• What is chemical equilibria?

  It is the state where reactants and products are balanced.
• What does the concept of reversibility in thermodynamics imply?

  Reversible processes can proceed in both directions.
• How is the equilibrium constant related to Gibb’s free energy?

  It indicates the spontaneity of a chemical reaction.
• What is Gibb’s free energy a function of?

  Changes in entropy and enthalpy at temperature.
• Under what condition does the relationship of Gibb’s free energy hold true?

  When the process occurs at constant temperature.
• What does the second law of thermodynamics state about spontaneous processes?

  They lead to an increase in entropy.
• What is the Gibb’s free energy value for spontaneous processes?

  ΔG must be less than zero (ΔG < 0).

  
• What is the Gibb’s free energy value for non-spontaneous processes?

  ΔG must be greater than zero (ΔG > 0).

  
• If ΔH > 0 and ΔS < 0, what can be concluded about the reaction's spontaneity?

  The reaction always progresses non-spontaneously.
• What does the third law of thermodynamics allow us to determine?

  Absolute entropy values of materials.
• Why can we only monitor changes in enthalpy or internal energy?

  Absolute values cannot be determined.
• What defines a system that has reached equilibrium?

  • Maximum work done by the system achieved
  • Minimum work done on the system required
  • Rate of forward and reverse reactions are equal
• How can chemical reactions occur in terms of direction?

  They can occur forward or reverse.
• What is the equilibrium constant denoted by?

  K
• How is the equilibrium constant expressed?

  Using concentrations of reactants and products.
• What is a characteristic of equilibrium constants?

  They are dimensionless and have no units.
• What does a small equilibrium constant indicate?

  It is characteristic of non-spontaneous reactions.
• What does a large equilibrium constant indicate?

  It is characteristic of spontaneous reactions.
• What are the key points summarised in thermodynamics regarding equilibrium?

  • Entropy of a perfect crystal at 0 K is zero
  • Maximum work done by the system at equilibrium
  • Rate of forward reaction equals rate of backward reaction
• What is the implication of Gibb's free energy for reactions?

  It indicates spontaneity of reactions.
• What does a reaction with an equilibrium constant close to 1 imply?

  It doesn't favour either side of the reaction.