13.3.1 Concept of Entropy (S)

• Entropy (S) is a measure of the disorder or randomness in a system.
• What is Boltzmann's equation for entropy?

  $S =$$k \ln W$
• The state of matter with the highest entropy is gas.
• Entropy increases when particles have more freedom to arrange themselves.
• During melting, entropy increases because the liquid phase has more disorder than the solid phase.
• Exothermic reactions always lead to an increase in entropy.

  False
• What are three key factors that affect entropy?

  Number of Particles, Phase Changes, Temperature
• Boiling a liquid increases entropy more than melting a solid.
• Standard molar entropy is the entropy of one mole of a substance under standard conditions.
• What are the units of standard molar entropy?

  $J / (mol \cdot K)$
• Standard molar entropy values are always positive.
• Boltzmann's equation, $S =$$k \ln W$, relates entropy to the number of microstates.
• Entropy (S) measures the disorder or randomness in a system
• What is Boltzmann's equation for entropy?

  $S =$$k \ln W$
• A solid has higher entropy than a gas.

  False
• A liquid has moderate entropy
• Match the state of matter with its entropy:

  Solid ↔️ Low

  Liquid ↔️ Moderate

  Gas ↔️ High
• A gas has higher entropy than a solid due to its more disordered particle arrangement
• Higher entropy implies more disorder and greater freedom for particles.
• What is the value of Boltzmann's constant in Boltzmann's equation?

  1.38 \times 10^{ - 23} \, J / K</latex>
• When ice melts, water molecules gain more freedom
• Entropy is directly related to the number of microstates available in a system.
• Arrange the following physical processes in order of increasing entropy:

  1️⃣ Freezing (Liquid to Solid)

  2️⃣ Boiling (Liquid to Gas)

  3️⃣ Melting (Solid to Liquid)
• Melting increases entropy because the liquid phase has more disordered particle arrangement
• More particles in a system generally increase its entropy.
• Higher temperatures lead to more kinetic energy and thus higher entropy
• What does standard molar entropy measure?

  Degree of disorder
• Standard molar entropy is always a positive value.
• The entropy change for a reaction is calculated using standard molar entropies of products
• What is the Boltzmann equation used to relate entropy to?

  Microstates
• Boltzmann's constant is a positive value.
• The second law of thermodynamics states that the total entropy of an isolated system can only increase or remain constant
• A process with a positive change in entropy is spontaneous.