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Entropy definitions

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Terms in this set (15)

  • Entropy
    A measure of disorder or randomness in a system, increasing as systems move from solid to liquid to gas.
  • Second Law of Thermodynamics
    States that entropy of a system increases spontaneously, leading to more disorder.
  • Third Law of Thermodynamics
    At absolute zero (0 Kelvin), the entropy of a perfect crystal is zero.
  • Standard Molar Entropy
    Entropy of one mole of a substance at standard conditions (25°C, 1 atm).
  • Spontaneity
    A process is spontaneous if the total entropy change (ΔS total) is greater than zero.
  • System
    The part of the universe being studied, often a balanced chemical equation.
  • Surroundings
    Everything outside the system, contributing to the total entropy change.
  • Delta S
    Change in entropy, positive for increasing disorder, negative for increasing order.
  • Troughton's Rule
    States that the entropy of vaporization for many substances is about 88 J/mol·K.
  • Boltzmann Equation
    Relates entropy change to work, using the constant k derived from R and Avogadro's number.
  • Absolute Zero
    The temperature at which entropy reaches zero, equivalent to 0 Kelvin.
  • Natural State
    The state of an element when it is by itself or connected to copies of itself.
  • Delta H
    Change in enthalpy, often calculated as products minus reactants in a reaction.
  • Delta G
    Change in Gibbs free energy, indicating spontaneity when negative.
  • Work
    Calculated as negative pressure times change in volume, related to entropy change.