entropy

• spontaneous process is one that takes place without continuous intervention from us
• entropy of a substance increases with increasing temperature
• a system is more energetically stable when it is distorted
• the more distorted the higher the entropy
• entropy 


  is a property of matter that is associated with the degree of disorder of particles
• which state is the most distorted

  gas
• which state is the least distorted

  solid
• solid 


  ordered

  regular arrangement of particles

  low entropy
• gas

  distorted

  random arrangement

  high entropy
• for a reaction to be spontaneous the total entropy change must be positive
• when a gas condenses to form a liquid or solid, its entropy decreases as the molecules become more ordered
• when a solid melts, its entropy increases as the molecules become less ordered
• when a liquid boils, its entropy increases as the molecules become less ordered
• equation for total entropy change 


  entropy of system - entropy of surroundings
• equation for entropy of system 


  sum of entropy of products minus reactants

  
• equation for surroundings 


  enthalpy change divided by temperature in K

  
• total entropy will be positive if 


  entropy of system and entropy of surroundings are positive

  if one is more positive than the other
• dissolving ionic solids 


  for an ionic solid to be soluble the total entropy change must be positive