State Functions

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State Functions

• State functions or state properties are
  properties that depend only on the state of the
  system
• State functions are independent on how the sample
  was prepared
• P, V, U, and H are state functions
• ?U ? dU Uf Ui
• A system undergoing a change in which U changes
  from Ui to Uf
• The value of ?U depends only on the initial and
  final states but is independent on the process
• dU is an exact differential

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Path Functions

• Properties that relate to the preparation of the
  state are called path functions
• Work and heat are path functions
• Work and heat for a particular process depend on
  how the change was made
• dU dq dw
• dq and dw are inexact differentials
• the values of q and w are path dependent

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The Slope Formula

• For a closed system of constant composition any
  state function is a function of only two state
  variables
• U is a function of volume and temperature, U(V,T)
• H is a function of temperature and pressure,
  H(T,P)
• V is a function of temperature and pressure,
  V(T,P)
• A change in temperature and pressure will affect
  the volume of a system. The change in volume, dV,
  is given by
• dV (?V/?T)p dT (?V/?P)T dp (The Slope
  Formula)
• (?V/?T)p expresses the variation of V with T at
  constant pressure
• values of (?V/?T)p and (?V/?p)T can be
  experimentally determined

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